Oracle® Database

XStream Guide

12c Release 1 (12.1)

E53119-02

December 2014

Oracle Database XStream Guide, 12c Release 1 (12.1)

E53119-02

Copyright © 2009, 2014, Oracle and/or its affiliates. All rights reserved.

Primary Author:  Randy Urbano

Contributors:  Lance Ashdown, Alan Downing, Thuvan Hoang, Richard Huang, Joydip Kundu, Belinda Leung, Tianshu Li, Edwina Lu, Rui Mao, Pat McElroy, Valarie Moore, Srikanth Nalla, Partha Raghunathan, Ashish Ray, Jim Stamos, Byron Wang, Rod Ward, Lik Wong, Haobo Xu, Kevin Xu, Jun Yuan, Lei Zheng

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Contents

Preface

- Audience

- Documentation Accessibility

- Related Documents

- Conventions

Changes in This Release for Oracle Database XStream Guide

- Changes in Oracle Database 12c Release 1 (12.1)

Part I XStream General Concepts and Use Cases

1 Introduction to XStream

- About XStream

- Purpose of XStream

- XStream Use Cases

- Replicating Data Changes with Non-Oracle Databases

- Using Files to Store Data Changes

- XStream Demo That Replicates Database Changes Using Files

- Sharing Data Changes with a Client-Side Memory Cache

- Prerequisites for XStream

- XStream Security Models

- Tasks and Tools for XStream

- XStream Tasks

- XStream Tools

2 General XStream Concepts

- Logical Change Records (LCRs)

- Row LCRs

- Row LCR Subtypes

- DDL LCRs

- Extra Information in Row LCRs and DDL LCRs

- Sequence LCRs

- Position Order in an LCR Stream

- Rules and Rule Sets

- Rules and Rule Sets Defined

- Rule Sets and XStream Components

- System-Created Rules and XStream

- XStream System-Created Rule Procedures

- Global Rules

- Schema Rules

- Table Rules

- Subset Rules

- System-Created Rules and a Multitenant Environment

- Rule-Based Transformations

- Declarative Rule-Based Transformations

- Declarative Rule-Based Transformation Ordering

- Evaluating Transformation Ordering

- Row Migration Transformation Ordering

- User-Specified Declarative Transformation Ordering

- Considerations for Rule-Based Transformations

- XStream and the Oracle Streams Performance Advisor

- XStream Components

- XStream Out Apply Subcomponents

- XStream In Apply Subcomponents

- Topology and Stream Paths

- XStream and Component-Level Statistics

- The UTL_SPADV Package

- Collecting XStream Statistics Using the UTL_SPADV Package

- Showing XStream Statistics on the Command Line

- Interpreting SHOW_STATS Output

- Showing XStream Statistics in an HTML Report

- Interpreting the HTML Report From SHOW_STATS_HTML

- XStream and SQL Generation

- Interfaces for Performing SQL Generation

- SQL Generation Formats

- SQL Generation and Data Types

- SQL Generation and Automatic Data Type Conversion

- SQL Generation and Character Sets

- Sample Generated SQL Statements

- Sample Generated SQL Statements for the hr.employees Table

- Sample Generated SQL Statements for a Table With LOB Columns

- SQL Generation Demo

Part II XStream Out

3 XStream Out Concepts

- Introduction to XStream Out

- Capture Processes

- Capture Process Overview

- Data Types Captured by a Capture Process

- ID Key LCRs

- Types of DML Changes Captured by Capture Processes

- Local Capture and Downstream Capture

- Local Capture

- Downstream Capture

- Capture Processes and RESTRICTED SESSION

- Capture Process Subcomponents

- Capture Process States

- Capture Process Parameters

- Capture Process Checkpoints and XStream Out

- Required Checkpoint SCN

- Maximum Checkpoint SCN

- Checkpoint Retention Time

- SCN Values Related to a Capture Process

- Captured SCN and Applied SCN

- First SCN and Start SCN

- Outbound Servers

- Overview of Outbound Servers

- Data Types Supported by Outbound Servers

- Apply User for an Outbound Server

- Outbound Servers and RESTRICTED SESSION

- Outbound Server Components

- Considerations for Outbound Servers

- Outbound Servers and Apply Parameters

- Position of LCRs and XStream Out

- Additional LCR Attributes Related to Position in XStream Out

- The Processed Low Position and Restartability for XStream Out

- Streaming Network Transmission

- XStream Out and Distributed Transactions

- XStream Out and Security

- The XStream Out Client Application and Security

- XStream Out Component-Level Security

- Privileges Required by the Capture User for a Capture Process

- Privileges Required by the Connect User for an Outbound Server

- XStream Out and Other Oracle Database Components

- XStream Out and Oracle Real Application Clusters

- Capture Processes and Oracle Real Application Clusters

- Queues and Oracle Real Application Clusters

- Propagations and Oracle Real Application Clusters

- Outbound Servers and Oracle Real Application Clusters

- XStream Out and Transparent Data Encryption

- Capture Processes and Transparent Data Encryption

- Propagations and Transparent Data Encryption

- Outbound Servers and Transparent Data Encryption

- XStream Out and Flashback Data Archive

- XStream Out and Recovery Manager

- RMAN and Local Capture Processes

- RMAN and Downstream Capture Processes

- XStream and Distributed Transactions

- XStream Out and a Multitenant Environment

4 Configuring XStream Out

- Preparing for XStream Out

- Decide How to Configure XStream Out

- Prerequisites for Configuring XStream Out

- Configure an XStream Administrator on All Databases

- Granting Additional Privileges to the XStream Administrator

- If Required, Configure Network Connectivity and Database Links

- Ensure That Each Source Database Is in ARCHIVELOG Mode

- Set the Relevant Initialization Parameters

- Configure the Streams pool

- If Required, Configure Supplemental Logging

- If Required, Configure Log File Transfer to a Downstream Database

- If Required, Add Standby Redo Logs for Real-Time Downstream Capture

- Configuring XStream Out

- Configuring an Outbound Server Using CREATE_OUTBOUND

- Adding an Additional Outbound Server to a Capture Process Stream

- Configuring an Outbound Server Using ADD_OUTBOUND

- Configuring XStream Out in a CDB

- Configuring XStream Out with Local Capture in a CDB

- Configuring XStream Out with Downstream Capture in CDBs

5 Managing XStream Out

- About Managing XStream Out

- Managing an Outbound Server

- Starting an Outbound Server

- Stopping an Outbound Server

- Setting an Apply Parameter for an Outbound Server

- Changing the Connect User for an Outbound Server

- Managing the Capture Process for an Outbound Server

- Checking Whether the DBMS_XSTREAM_ADM Package Can Manage a Capture Process

- Starting a Capture Process

- Stopping a Capture Process

- Setting a Capture Process Parameter

- Changing the Capture User of an Outbound Server's Capture Process

- Changing the Start SCN or Start Time of an Outbound Server's Capture Process

- Changing the Start SCN of an Outbound Server's Capture Process

- Changing the Start Time of an Outbound Server's Capture Process

- Setting the First SCN for a Capture Process

- Managing Rules for an XStream Out Configuration

- Adding Rules to an XStream Out Configuration

- Adding Schema Rules and Table Rules to an XStream Out Configuration

- Adding Subset Rules to an Outbound Server's Positive Rule Set

- Adding Rules With Custom Conditions to XStream Out Components

- Removing Rules from an XStream Out Configuration

- Removing Schema Rules and Table Rules From an XStream Out Configuration

- Removing Subset Rules from an Outbound Server's Positive Rule Set

- Removing Rules Using the REMOVE_RULE Procedure

- Managing Declarative Rule-Based Transformations

- Adding Declarative Rule-Based Transformations

- Adding a Declarative Rule-Based Transformation That Renames a Table

- Adding a Declarative Rule-Based Transformation That Adds a Column

- Overwriting Existing Declarative Rule-Based Transformations

- Removing Declarative Rule-Based Transformations

- Dropping Components in an XStream Out Configuration

- Removing an XStream Out Configuration

6 Monitoring XStream Out

- About Monitoring XStream Out

- Monitoring Session Information About XStream Out Components

- Monitoring XStream Out

- Displaying General Information About an Outbound Server

- Displaying Status and Error Information for an Outbound Server

- Displaying Information About an Outbound Server's Current Transaction

- Displaying Statistics for an Outbound Server

- Displaying the Processed Low Position for an Outbound Server

- Determining the Process Information for an Outbound Server

- Displaying the Apply Parameter Settings for an Outbound Server

- Monitoring the Capture Process for an Outbound Server

- Displaying Change Capture Information About Each Capture Process

- Displaying the Registered Redo Log Files for Each Capture Process

- Displaying Redo Log Files That Are Required by Each Capture Process

- Displaying SCN Values for Each Redo Log File Used by Each Capture Process

- Listing the Parameter Settings for Each Capture Process

- Determining the Applied SCN for Each Capture Process

- Displaying the Redo Log Scanning Latency for Each Capture Process

- Displaying the Extra Attributes Captured by a Capture Process

- Monitoring XStream Rules

- Monitoring Declarative Rule-Based Transformations

- Displaying Information About ADD COLUMN Transformations

- Displaying Information About RENAME TABLE Transformations

7 Troubleshooting XStream Out

- Diagnosing Problems with XStream Out

- Viewing Alerts

- Using the Streams Configuration Report and Health Check Script

- Checking the Trace File and Alert Log for Problems

- Capture Process Trace Files

- Logminer Trace Files

- Outbound Server Trace File

- Client Application Trace Files

- Problems and Solutions for XStream Out

- An OCI Client Application Cannot Attach to the Outbound Server

- Changes Are Failing to Reach the Client Application in XStream Out

- The Capture Process Is Missing Required Redo Log Files

- LCRs Streaming from an Outbound Server Are Missing Extra Attributes

- The XStream Out Client Application Is Unresponsive

- How to Get More Help with XStream Out

Part III XStream In

8 XStream In Concepts

- Introduction to XStream In

- The Inbound Server

- Overview of Inbound Servers

- Data Types Applied by Inbound Servers

- LCR Processing Options for Inbound Servers

- DML Handlers

- Error Handlers

- DDL Handlers

- Precommit Handlers

- Inbound Servers and RESTRICTED SESSION

- Inbound Server Components

- Considerations for Inbound Servers

- The Error Queue for an Inbound Server

- Position of LCRs and XStream In

- XStream In and Performance Considerations

- Optimizing XStream In Performance for Large Transactions

- Avoiding Potential Bottlenecks in Transaction Tracking

- Optimizing Transaction Apply Scheduling

- XStream In and Security

- The XStream In Client Application and Security

- XStream In Component-Level Security

- Privileges Required by the Apply User for an Inbound Server

- XStream In and Other Oracle Database Components

- XStream In and Oracle Real Application Clusters

- XStream In and Flashback Data Archive

- XStream In and Transportable Tablespaces

- XStream In and a Multitenant Environment

9 Configuring XStream In

- Preparing for XStream In

- Configure an XStream Administrator

- Granting Additional Privileges to the XStream Administrator

- Set the Relevant Initialization Parameters

- Configure the Streams pool

- If Required, Specify Supplemental Logging at the Source Database

- Configuring XStream In

10 Managing XStream In

- About Managing XStream In

- Starting an Inbound Server

- Stopping an Inbound Server

- Setting an Apply Parameter for an Inbound Server

- Changing the Apply User for an Inbound Server

- Managing Apply Errors

- Retrying Apply Error Transactions

- Retrying a Specific Apply Error Transaction

- Retrying All Error Transactions for an Inbound Server

- Deleting Apply Error Transactions

- Deleting a Specific Apply Error Transaction

- Deleting All Error Transactions for an Inbound Server

- Managing Eager Errors Encountered by an Inbound Server

- Dropping Components in an XStream In Configuration

11 Monitoring XStream In

- Displaying Session Information for Inbound Servers

- Displaying General Information About an Inbound Server

- Displaying the Status and Error Information for an Inbound Server

- Displaying Apply Parameter Settings for an Inbound Server

- Displaying the Position Information for an Inbound Server

- Checking for Apply Errors

- Displaying Detailed Information About Apply Errors

- Step 1: Grant Explicit SELECT Privilege on the ALL_APPLY_ERROR View

- Step 2: Create a Procedure that Prints the Value in an ANYDATA Object

- Step 3: Create a Procedure that Prints a Specified LCR

- Step 4: Create a Procedure that Prints All the LCRs in the Error Queue

- Step 5: Create a Procedure that Prints All the Error LCRs for a Transaction

12 Troubleshooting XStream In

- Diagnosing Problems with XStream In

- Viewing Alerts

- Checking the Trace File and Alert Log for Problems

- Problems and Solutions for XStream In

- XStream In Cannot Identify an Inbound Server

- Inbound Server Encounters an ORA-03135 Error

- How to Get More Help with XStream In

Part IV Appendixes

A Sample XStream Client Application

- About the Sample XStream Client Application

- Sample XStream Client Application for the Oracle Call Interface API

- Sample XStream Client Application for the Java API

B XStream Out Restrictions

- Capture Process Restrictions

- Unsupported Data Types for Capture Processes

- Unsupported Changes for Capture Processes

- Unsupported Schemas for Capture Processes

- Unsupported Table Types for Capture Processes

- Unsupported DDL Changes for Capture Processes

- Changes Ignored by a Capture Process

- NOLOGGING and UNRECOVERABLE Keywords for SQL Operations

- UNRECOVERABLE Clause for Direct Path Loads

- Supplemental Logging Data Type Restrictions

- Operational Requirements for Downstream Capture with XStream Out

- Capture Processes Do Not Support Oracle Label Security

- Propagation Restrictions

- Connection Qualifiers and Propagations

- Outbound Server Restrictions

- Unsupported Data Types for Outbound Servers

- Types of DDL Changes Ignored by an Outbound Server

- Apply Process Features That Are Not Applicable to Outbound Servers

- XStream Out Rule Restrictions

- Restrictions for Subset Rules

- XStream Out Rule-Based Transformation Restrictions

- Unsupported Data Types for Declarative Rule-Based Transformations

- XStream Out Limitations for Extended Data Types

C XStream In Restrictions

- Inbound Server Restrictions

- Unsupported Data Types for Inbound Servers

- Unsupported Data Types for Apply Handlers

- Types of DDL Changes Ignored by an Inbound Server

- Current Schema User Must Exist at Destination Database

- Inbound Servers Do Not Support Oracle Label Security

- XStream In Rule Restrictions

- Restrictions for Subset Rules

- XStream In Rule-Based Transformation Restrictions

- Unsupported Data Types for Declarative Rule-Based Transformations

- XStream In Limitations for Extended Data Types

Index

Preface

Oracle Database XStream Guide describes the features and functionality of XStream. This document contains conceptual information about XStream, along with information about configuring and managing an XStream environment. In addition, this document contains reference information related to XStream.

Audience

This guide is intended for database administrators who configure and manage XStream environments. To use this document, database administrators must be familiar with relational database concepts, SQL, distributed database administration, Oracle Streams concepts, PL/SQL, and the operating systems under which they run an XStream environment.

This guide is also intended for programmers who develop applications that use XStream. To use this document, programmers need knowledge of an application development language and relational database concepts.

Documentation Accessibility

For information about Oracle's commitment to accessibility, visit the Oracle Accessibility Program website at http://www.oracle.com/pls/topic/lookup?ctx=acc&id=docacc.

Access to Oracle Support

Oracle customers that have purchased support have access to electronic support through My Oracle Support. For information, visit http://www.oracle.com/pls/topic/lookup?ctx=acc&id=info or visit http://www.oracle.com/pls/topic/lookup?ctx=acc&id=trs if you are hearing impaired.

Related Documents

For more information, see the following documents:

- Oracle Database XStream Java API Reference

- Oracle Streams Concepts and Administration

- Oracle Streams Replication Administrator's Guide

- Oracle Call Interface Programmer's Guide

- Oracle Database 2 Day + Java Developer's Guide

- Oracle Database Java Developer's Guide

- Oracle Database Concepts

- Oracle Database Administrator's Guide

- Oracle Database SQL Language Reference

- Oracle Database PL/SQL Packages and Types Reference

- Oracle Database PL/SQL Language Reference

- Oracle Database Advanced Queuing User's Guide

Many of the examples in this book use the sample schemas of the sample database, which is installed by default when you install Oracle Database. Refer to Oracle Database Sample Schemas for information about how these schemas were created and how you can use them yourself.

Conventions

The following text conventions are used in this document:

Convention

Meaning

boldface

Boldface type indicates graphical user interface elements associated with an action, or terms defined in text or the glossary.

italic

Italic type indicates book titles, emphasis, or placeholder variables for which you supply particular values.

monospace

Monospace type indicates commands within a paragraph, URLs, code in examples, text that appears on the screen, or text that you enter.

Changes in This Release for Oracle Database XStream Guide

This preface contains:

- Changes in Oracle Database 12c Release 1 (12.1)

Changes in Oracle Database 12c Release 1 (12.1)

The following are changes in Oracle Database XStream Guide for Oracle Database 12c Release 1 (12.1).

New Features

The following features are new in this release:

- Support for Oracle Multitenant option
Oracle Multitenant option enables an Oracle database to contain a portable set of schemas, objects, and related structures that appears logically to an application as a separate database. This self-contained collection is called a pluggable database (PDB). A multitenant container database (CDB) contains PDBs. You can configure an XStream Out or XStream In environment that includes CDBs and PDBs.

See "XStream Out and a Multitenant Environment" and "XStream In and a Multitenant Environment".

- Eager apply of large transactions with XStream In
As a performance optimization, an XStream inbound server can use eager apply to begin to apply large transactions before it receives the commit logical change record (LCR).

See "Optimizing XStream In Performance for Large Transactions".

- Ability to eliminate apply progress tables with XStream In
You can configure XStream In to use the redo log to track its progress instead of an apply progress table to avoid potential bottlenecks in transaction processing.

See "Avoiding Potential Bottlenecks in Transaction Tracking".

- Optimized transaction apply scheduling with XStream In
When the constraints on the target tables match the constraints on the source tables, you can optimize dependency computation by setting the compute_lcr_dep_on_arrival apply parameter for an inbound server to Y.

See "Optimizing Transaction Apply Scheduling".

- New apply parameters
The following new apply parameters are added for XStream outbound servers:

- excludetag

- excludetrans

- excludeuser

- excludeuserid

- getapplops

- getreplicates

The following new apply parameters are added for XStream inbound servers:

- compute_lcr_dep_on_arrival

- eager_size

- enable_xstream_table_stats

- handlecollisions

- max_parallelism

- optimize_progress_table

- optimize_self_updates

- suppresstriggers

See Oracle Database PL/SQL Packages and Types Reference for information about these apply parameters.

- New capture process parameters
The following new capture process parameters are added for XStream Out configurations:

- excludetag

- include_objects

- inline_lob_optimization

- use_rac_service

See Oracle Database PL/SQL Packages and Types Reference for information about these apply parameters.

- Trusted and untrusted security models
You can implement the XStream security model that best fits with your organization's requirements.

See "XStream Security Models".

- Support for the increased size limit for VARCHAR2, NVARCHAR2, and RAW data types
XStream Out and XStream In support the increased size limit for the VARCHAR2, NVARCHAR2, and RAW data types.

See "Data Types Captured by a Capture Process" and "Data Types Applied by Inbound Servers".

- Support for XMLType stored object relationally or as binary XML
XStream Out and XStream In support XMLType stored object relationally or as binary XML.

See "Data Types Captured by a Capture Process" and "Data Types Applied by Inbound Servers".

- Support SecureFiles LOB columns stored using Advanced LOB Deduplication
XStream supports changes to SecureFiles LOB columns stored using Advanced LOB Deduplication.

- HTML reports generated by the UTL_SPADV package
The SHOW_STATS_HTML procedure in the UTL_SPADV package generates HTML output that includes the statistics gathered by the COLLECT_STATS and START_MONITORING procedures in the same package.

See "The UTL_SPADV Package" and Oracle Database PL/SQL Packages and Types Reference.

Part I

XStream General Concepts and Use Cases

This part contains the following chapters:

- Chapter 1, "Introduction to XStream"

- Chapter 2, "General XStream Concepts"

1 Introduction to XStream

This chapter introduces you to XStream. XStream enables information sharing with outstanding performance and usability.

This chapter contains the following topics:

- About XStream

- Purpose of XStream

- XStream Use Cases

- Prerequisites for XStream

- XStream Security Models

- Tasks and Tools for XStream

About XStream

XStream consists of Oracle Database components and application programming interfaces (APIs) that enable client applications to receive data changes from an Oracle database and send data changes to an Oracle database. These data changes can be shared between Oracle databases and other systems. The other systems include non-Oracle databases, non-RDBMS Oracle products, file systems, third party software applications, and so on. A client application is designed by the user for specific purposes and use cases.

XStream consists of two major features: XStream Out and XStream In. XStream Out provides Oracle Database components and APIs that enable you to share data changes made to an Oracle database with other systems. XStream Out can retrieve both data manipulation language (DML) and data definition language (DDL) changes from the redo log and send these changes to a client application that uses the APIs, as shown in Figure 1-1.

Figure 1-1 XStream Out

XStream In provides Oracle Database components and APIs that enable you to share data changes made to other systems with an Oracle database. XStream In can apply these changes to database objects in the Oracle database, as shown in Figure 1-2.

Figure 1-2 XStream In

XStream uses the capture and apply features of the Oracle database. These features enable the following functionality for XStream:

- The logical change record (LCR) format for streaming database changes
An LCR is a message with a specific format that describes a database change. If the change was a data manipulation language (DML) operation, then a row LCR encapsulates each row change resulting from the DML operation. One DML operation might result in multiple row changes, and so one DML operation might result in multiple row LCRs. If the change was a data definition language (DDL) operation, then a single DDL LCR encapsulates the DDL change.

See "Logical Change Records (LCRs)" for more information about LCRs.

- Rules and rule sets that control behavior, including inclusion and exclusion rules
Rules enable the filtering of database changes at the database level, schema level, table level, and row/column level.

See "Rules and Rule Sets" for more information about LCRs.

- Rule-based transformations that modify captured data changes

- Support for most data types in the database, including LOBs, LONG, LONG RAW, and XMLType

- Customized configurations, including multiple inbound streams to a single database instance, multiple outbound streams from a single database instance, multiple outbound streams from a single capture process, and so on

- Full-featured apply for XStream In, including apply parallelism for optimal performance, SQL generation, conflict detection and resolution, error handling, and customized apply with apply handlers

Note:
In both XStream Out and XStream In configurations, the client application must use a dedicated server connection.

See Also:

- Chapter 9, "Configuring XStream In"

- Oracle Database PL/SQL Packages and Types Reference

Purpose of XStream

Some customers, especially Independent Software Vendors (ISVs) and partners, need access to the Oracle database as a platform for their own information sharing products, such as file-level replication, middle-tier caches or even to support replication between Oracle and non-Oracle data stores. XStream provides these customers with fast, real-time access to changes made in the Oracle database.

XStream is a programmatic interface that allows client applications to connect to the Oracle database and attach directly into the database capture or apply process. A client application can take advantage of a high performing capture mechanism by attaching to the XStream outbound server to directly access the stream of changes from an Oracle database. XStream Out streams logical change records (LCRs) to the client application in committed transaction order.

To apply changes to the Oracle database, a client application can hook directly into the XStream inbound server. The application provides the inbound server with LCRs in transactional order and can take advantage of the high performance of the database apply engine to apply the changes to the Oracle database.

XStream Use Cases

XStream provides a flexible infrastructure for sharing information between Oracle data sources and non-Oracle data sources. You can use XStream to meet the data and informational sharing needs of various organizations. This section describes common XStream use cases.

Each XStream use case in this section contains three main elements:

- A general description of the use case as it applies to both XStream Out and XStream In

- A specific scenario for XStream Out

- A specific scenario for XStream In

In each XStream Out use case, the following components and actions send Oracle Database changes to a client application:

- A capture process captures data changes made to an Oracle database.

- XStream Out sends these changes, in the form of logical change records (LCRs), to an outbound server.

- The outbound server sends the LCRs to a client application.

How the client application processes the LCRs is different for each use case.

In each XStream In use case, the following components and actions send Oracle Database changes to an inbound server:

- A client application gathers data changes from an external data source and sends them to an inbound server in the form of LCRs.

- The inbound server receives the LCRs from a client application.

- The inbound server can apply the data changes to database objects in an Oracle database. The inbound server can also process the LCRs in a customized way.

How the client application gathers the data changes is different for each use case.

You can use XStream to accomplish the following goals:

- Replicating Data Changes with Non-Oracle Databases

- Using Files to Store Data Changes

- Sharing Data Changes with a Client-Side Memory Cache

See Also:

- "Introduction to XStream Out"

- "Introduction to XStream In"

Replicating Data Changes with Non-Oracle Databases

Replication is generally used to improve availability and to improve performance by spreading the network load over multiple regions and servers. XStream enables you replicate data changes made to an Oracle database with other Oracle databases and with non-Oracle data sources.

You can configure a heterogeneous replication environment with XStream. Replication is generally used to improve availability and to improve performance by spreading the network load over multiple regions and servers. In a heterogeneous replication environment, data is replicated between databases from different vendors.

XStream Out can send data changes made to an Oracle database to a non-Oracle database. Specifically, the client application connects to the outbound server and receives changes made to tables within the Oracle database. The client application then applies the data changes in the LCRs to the non-Oracle database. The client application can process the LCRs in any customized way before applying them.

XStream In can receive data changes made to a non-Oracle database. Specifically, the client application gathers the data changes made to the non-Oracle database, formats these changes into LCRs, and sends these LCRs to an inbound server. The inbound server applies the changes in the LCRs to the Oracle database.

Note:
Oracle GoldenGate is a complete solution for replicating data between Oracle and non-Oracle databases. Oracle GoldenGate documentation for more information.

Using Files to Store Data Changes

Some environments use files to store data changes. Typically, files store data changes for the following reasons:

- To process data changes in an environment that has no physical network or a limited physical network. For example, some locations do not have a physical network for security reasons.

- To process data changes in an environment that uses disconnected computing. For example, a salesperson might fill orders on a laptop at various locations without a network connection, and then update a primary database over the network once a day.

- To process data changes in an environment that uses satellite communications. In this case, a bulk transfer of files is more efficient than incremental changes over the network.
XStream Out can send Oracle Database changes to a file in a file system. Specifically, the client application writes the data changes in LCRs to the file. The client application can process the LCRs in any customized way before writing them to the file, and the file can reside on the computer system running the client application or on a different computer system. Using SQL generation, the client application can also write the SQL statement required to perform the change encapsulated in a row LCR to a file.

XStream In can send data changes from a file to an Oracle database. Specifically, the client application reads the data changes from the file and sends the changes, in the form of LCRs, to an inbound server.

See Also:
"XStream and SQL Generation"

XStream Demo That Replicates Database Changes Using Files

A demo is available that creates sample client applications that perform file-based replication using the XStream APIs. Specifically, at one database, the demo creates an XStream Out configuration that captures database changes and sends the LCRs to an outbound server. A client application attaches to the outbound server and writes the database changes to a file.

At a different database, the demo creates an XStream In client application that attaches to an inbound server, reads the changes in the file, and sends them in the form of LCRs to the inbound server. The inbound server applies the changes to the database objects at the destination database.

This demo is available in the following location:

$ORACLE_HOME/rdbms/demo/xstream/fbr

Sharing Data Changes with a Client-Side Memory Cache

Some environments cache data in memory to improve performance. Cached data can provide low response times and high throughput for systems that require the best possible performance. XStream can share data changes incrementally with a client side memory cache.

XStream Out can incrementally refresh a client-side memory cache by sending Oracle database changes to a memory cache. Specifically, the client application applies the data changes in the LCRs to the memory cache. The client application can process the LCRs in any customized way before applying them, and the memory cache can reside on the computer system running the client application or on a different computer system.

XStream In can incrementally retrieve data changes from a memory cache. Specifically, the client application retrieves the data changes and sends the changes, in the form of LCRs, to an inbound server. The memory cache can reside on the computer system running the client application or on a different computer system.

Prerequisites for XStream

Using the XStream APIs requires purchasing a license for the Oracle GoldenGate product. See the Oracle GoldenGate documentation for more information.

In addition, this document assumes that you have the following skills:

- Knowledge of relational database concepts and Oracle Database concepts
XStream includes components that run in an Oracle database. To use XStream successfully, you must be able to administer an Oracle Database.

See Oracle Database Concepts for information about this topic.

- Knowledge of distributed databases
An XStream environment can include multiple data sources, including Oracle databases and non-Oracle data sources. You should understand distributed database concepts before using XStream.

See Oracle Database Administrator's Guide for information about this topic.

- Knowledge of SQL and PL/SQL
To administer an Oracle database and the XStream components running in an Oracle database, you must know how to use SQL and PL/SQL.

See Oracle Database SQL Language Reference, Oracle Database PL/SQL Language Reference, and Oracle Database PL/SQL Packages and Types Reference for information about this topic.

- Knowledge of application programming
XStream Out sends data changes to a client application for processing. XStream In receives data changes from a client application. You use the Oracle Call Interface (OCI) API or the Java API to create a client application that communicates with XStream.

See Oracle Call Interface Programmer's Guide for information about the OCI API.

See Oracle Database 2 Day + Java Developer's Guide and Oracle Database Java Developer's Guide for information about the Java API.

XStream Security Models

With XStream, you can implement the security model that best fits with your organization's requirements.

XStream supports two modes of security:

- XStream Trusted User Model
An XStream administrator configured with the trusted user model can manage any XStream configuration, has more database privileges than an untrusted counterpart, and can monitor XStream with DBA_ views.

The trusted user model is easier to implement than the untrusted user model, especially in an environment with multiple XStream configurations.

- XStream Untrusted User Model
An XStream administrator configured with the untrusted user model (also referred to as the minimum privilege model) can only manage XStream configurations owned by the untrusted user administrator. This model offers fine-grained administrative security because you can designate different untrusted user administrators to access different resources in the XStream environment. You can configure one or more XStream untrusted users and each of these users only has the minimum privileges required for the tasks that they are assigned. This strategy gives you the ability to isolate access and privileges to certain XStream resources. The untrusted administrator can monitor XStream with ALL_ views

For example, you might want to use the untrusted user model for situations where the capture process requires more privileges than the client process. You can then assign a different user for the client process that only has the privileges it requires.

Government and commercial organizations implement a variety of software and hardware security architectures to protect and control access to data and applications. Compliance with industry-specific service level agreements (SLAs), audits, security laws and regulations may require a separation of duties and responsibilities, and controlled access to data. These types of security criteria and restrictions suit the untrusted user model where you can designate different users and privileges to secure resources.

See Also :

- "XStream Out and Security"

- "XStream In and Security"

- "Configure an XStream Administrator on All Databases"

- "Configure an XStream Administrator"

Tasks and Tools for XStream

This section describes the common tasks you perform for XStream and the tools to use to complete the tasks.

This section contains the following topics:

- XStream Tasks

- XStream Tools

XStream Tasks

The common tasks for XStream are the following:

- Configure XStream
Configuring XStream involves preparing an Oracle Database for XStream, creating the Oracle Database components used by XStream, and creating one or more client applications that communicate with the Oracle Database.

See Chapter 4, "Configuring XStream Out" and Chapter 9, "Configuring XStream In" for information about this task.

- Administer XStream
Administering XStream involves managing the Oracle Database components used by XStream. It also involves managing the rules and rule sets used by these components. It might also require modifications to a client application.

See Chapter 5, "Managing XStream Out" and Chapter 10, "Managing XStream In" for information about this task.

- Monitor XStream
Monitoring XStream involves viewing Oracle Enterprise Manager Cloud Control pages related to XStream and querying data dictionary views related to XStream.

See the Oracle Enterprise Manager Cloud Control online help, Chapter 6, "Monitoring XStream Out" and Chapter 11, "Monitoring XStream In" for information about this task.

XStream Tools

Use the following tools to complete the tasks for XStream:

- SQL and PL/SQL
You can use SQL and PL/SQL to configure, administer, and monitor XStream. SQL enables you to create an XStream administrator and monitor XStream using data dictionary views. Several Oracle-supplied PL/SQL packages enable you to configure and manage XStream.

See Oracle Database SQL Language Reference, Oracle Database Reference, Oracle Database PL/SQL Language Reference, and Oracle Database PL/SQL Packages and Types Reference for information about this topic.

- Oracle Enterprise Manager Cloud Control
You can use Oracle Enterprise Manager Cloud Control to manage and monitor XStream components. You can also use Oracle Enterprise Manager Cloud Control to view information about the LCRs that are streaming in an XStream configuration.

See the Oracle Enterprise Manager Cloud Control online help for more information about this topic.

- The OCI API and Java API
You can use the XStream OCI API and XStream Java API to create client application that communicate with XStream. These applications can work with XStream Out to stream LCRs out of an Oracle Database, and these applications can work with XStream In to stream LCRs into an Oracle Database.

See Oracle Call Interface Programmer's Guide for information about the OCI API.

See Oracle Database XStream Java API Reference for information about the XStream Java API, and see Oracle Database 2 Day + Java Developer's Guide and Oracle Database Java Developer's Guide for information about the Java API.

2 General XStream Concepts

This chapter describes general XStream concepts that apply to both XStream Out and XStream In.

This chapter contains these topics:

- Logical Change Records (LCRs)

- Rules and Rule Sets

- Rule-Based Transformations

- XStream and the Oracle Streams Performance Advisor

- XStream and SQL Generation

See Also:

- Chapter 3, "XStream Out Concepts"

- Chapter 8, "XStream In Concepts"

Logical Change Records (LCRs)

An LCR is a message with a specific format that describes a database change. There are three types of LCRs: row LCRs, DDL LCRs, and sequence LCRs. In XStream, an LCR is the basic unit of information that describes a database change.

In an XStream Out configuration, a capture process can capture LCRs and send them to an outbound server. The outbound server can send the LCRs to the XStream client application.

In an XStream In configuration, an XStream client application can construct LCRs and send them to an inbound server. The inbound server can apply the database changes directly to the database object in the database, or the inbound server can process the LCRs in a customized way.

This section contains the following topics:

- Row LCRs

- DDL LCRs

- Extra Information in Row LCRs and DDL LCRs

- Sequence LCRs

- Position Order in an LCR Stream

Row LCRs

A row LCR describes a change to the data in a single row or a change to a single LOB column, LONG column, LONG RAW column, or XMLType column in a row. The change results from a data manipulation language (DML) statement or a piecewise operation. It may help to think of a row LCR as a DML LCR. For example, a single DML statement can insert or merge multiple rows into a table, can update multiple rows in a table, or can delete multiple rows from a table.

Since a single DML statement can affect more than one row, the capture process creates a row LCR for each row that is changed by the DML statement. Row LCRs represent the data changes made by a SQL or PL/SQL procedure invocation.

Each row LCR is encapsulated in an object of LCR$_ROW_RECORD type. Table 2-1 describes the attributes that are present in each row LCR.

Table 2-1 Attributes Present in All Row LCRs

Attribute

Description

source_database_name

The name of the source database where the row change occurred.

If the LCRs originated in a multitenant container database (CDB), then this attribute specifies the global name container where the row change occurred.

command_type

The type of DML statement that produced the change, either INSERT, UPDATE, DELETE, LOB ERASE, LOB WRITE, or LOB TRIM.

object_owner

The schema name that contains the table with the changed row.

object_name

The name of the table that contains the changed row.

tag

A raw tag that you can use to track the LCR.

transaction_id

The identifier of the transaction in which the DML statement was run.

scn

The system change number (SCN) at the time when the change was made.

old_values

The old column values related to the change. These are the column values for the row before the DML change. If the type of the DML statement is UPDATE or DELETE, then these old values include some or all of the columns in the changed row before the DML statement. If the type of the DML statement is INSERT, then there are no old values. For UPDATE and DELETE statements, row LCRs created by a capture process can include some or all of the old column values in the row.

new_values

The new column values related to the change. These are the column values for the row after the DML change. If the type of the DML statement is UPDATE or INSERT, then these new values include some or all of the columns in the changed row after the DML statement. If the type of the DML statement is DELETE, then there are no new values. For UPDATE and INSERT statements, row LCRs created by a capture process can include some or all of the new column values in the row.

position

A unique identifier of RAW data type for each LCR. The position is strictly increasing within a transaction and across transactions.

LCR position is commonly used in XStream configurations.

See "Position Order in an LCR Stream".

root_name

If the LCR originated in a CDB, then this attribute specifies the global name of the root in the CDB.

If the LCR originated in a non-CDB, then this attribute is the same as the source_database_name attribute.

Row LCRs that were captured by a capture process in an XStream Out configuration contain additional attributes. Table 2-2 describes these additional attributes. These attributes are not present in row LCRs constructed by an XStream client application in an XStream In configuration.

Table 2-2 Additional Attributes in LCRs Captured by a Capture Process

Attribute

Description

commit_scn

The commit system change number (SCN) of the transaction to which the LCR belongs.

commit_scn_from_position

The commit system change number (SCN) of a transaction determined by the input position, which is generated by an XStream outbound server.

commit_time

The commit time of the transaction to which the LCR belongs.

compatible

The minimal database compatibility required to support the LCR.

instance_number

The instance number of the database instance that made the change that is encapsulated in the LCR. Typically, the instance number is relevant in an Oracle Real Application Clusters (Oracle RAC) configuration.

lob_information

The LOB information for the column, such as NOT_A_LOB or LOB_CHUNK.

lob_offset

The LOB offset for the specified column in the number of characters for CLOB columns and the number of bytes for BLOB columns.

lob_operation_size

The operation size for the LOB column in the number of characters for CLOB columns and the number of bytes for BLOB columns.

long_information

The LONG information for the column, such as NOT_A_LONG or LONG_CHUNK.

row_text

The SQL statement for the change that is encapsulated in the row LCR.

scn_from_position

The SCN of the LCR.

source_time

The time when the change in an LCR captured by a capture process was generated in the redo log of the source database, or the time when a persistent LCR was created.

xml_information

The XML information for the column, such as NOT_XML, XML_DOC, or XML_DIFF.

Row LCR Subtypes

A row LCR can also contain transaction control statements. These row LCRs contain transaction control directives such as COMMIT and ROLLBACK. Such row LCRs are internal and can be used by outbound servers, inbound servers, and XStream client applications to maintain transaction consistency.

See Also:
Oracle Database PL/SQL Packages and Types Reference

DDL LCRs

A DDL LCR describes a data definition language (DDL) change. A DDL statement changes the structure of the database. For example, a DDL statement can create, alter, or drop a database object.

Each DDL LCR is encapsulated in an object of LCR$_DDL_RECORD type. Table 2-3 describes the attributes that are present in each DDL LCR.

Table 2-3 Attributes Present in All DDL LCRs

Attribute

Description

source_database_name

The name of the source database where the DDL change occurred.

If the LCRs originated in a CDB, then this attribute specifies the global name of the container where the DDL change occurred.

command_type

The type of DDL statement that produced the change, for example ALTER TABLE or CREATE INDEX.

object_owner

The schema name of the user who owns the database object on which the DDL statement was run.

object_name

The name of the database object on which the DDL statement was run.

object_type

The type of database object on which the DDL statement was run, for example TABLE or PACKAGE.

ddl_text

The text of the DDL statement.

logon_user

The logon user, which is the user whose session executed the DDL statement.

current_schema

The schema that is used if no schema is specified for an object in the DDL text.

base_table_owner

The base table owner. If the DDL statement is dependent on a table, then the base table owner is the owner of the table on which it is dependent.

base_table_name

The base table name. If the DDL statement is dependent on a table, then the base table name is the name of the table on which it is dependent.

tag

A raw tag that you can use to track the LCR.

transaction_id

The identifier of the transaction in which the DDL statement was run.

scn

The system change number (SCN) at the time when the change was made.

position

A unique identifier of RAW data type for each LCR. The position is strictly increasing within a transaction and across transactions.

LCR position is commonly used in XStream configurations.

See "Position Order in an LCR Stream".

edition_name

The name of the edition in which the DDL statement was executed.

root_name

If the LCR originated in a CDB, then this attribute specifies the global name of the root in the CDB.

If the LCR originated in a non-CDB, then this attribute is the same as the source_database_name attribute.

DDL LCRs that were captured by a capture process contain additional attributes. Table 2-4 describes these additional attributes. These attributes are not present in DDL LCRs constructed by an XStream client application in an XStream In configuration.

Table 2-4 Additional Attributes in DDL LCRs Captured by a Capture Process

Attribute

Description

commit_scn

The commit system change number (SCN) of the transaction to which the LCR belongs.

commit_scn_from_position

The commit SCN of a transaction determined by the input position, which is generated by an XStream outbound server.

commit_time

The commit time of the transaction to which the LCR belongs.

compatible

The minimal database compatibility required to support the LCR.

instance_number

The instance number of the database instance that made the change that is encapsulated in the LCR. Typically, the instance number is relevant in an Oracle Real Application Clusters (Oracle RAC) configuration.

scn_from_position

The SCN of the LCR.

source_time

The time when the change in an LCR captured by a capture process was generated in the redo log of the source database, or the time when a persistent LCR was created.

Note:
Both row LCRs and DDL LCRs contain the source database name of the database where a change originated. To avoid problems, Oracle recommends that you do not change the global name of the source database after a capture process has started capturing changes.

See Also:

- Oracle Call Interface Programmer's Guide for a complete list of the types of DDL statements in the "SQL Command Codes" table

- Oracle Database PL/SQL Packages and Types Reference

Extra Information in Row LCRs and DDL LCRs

In addition to the information discussed in the previous sections, row LCRs and DDL LCRs optionally can include the extra information (or LCR attributes) described in Table 2-4.

Table 2-5 Extra Attributes in LCRs

Attribute

Description

row_id

The rowid of the row changed in a row LCR. This attribute is not included in DDL LCRs or row LCRs for index-organized tables.

serial#

The serial number of the session that performed the change captured in the LCR.

session#

The identifier of the session that performed the change captured in the LCR.

thread#

The thread number of the instance in which the change captured in the LCR was performed. Typically, the thread number is relevant only in an Oracle Real Application Clusters (Oracle RAC) environment.

tx_name

The name of the transaction that includes the LCR.

username

The name of the current user who performed the change captured in the LCR.

You can use the INCLUDE_EXTRA_ATTRIBUTE procedure in the DBMS_CAPTURE_ADM package to instruct a capture process to capture one or more extra attributes.

See Also:

- Oracle Database PL/SQL Packages and Types Reference for more information about the INCLUDE_EXTRA_ATTRIBUTE procedure

- Oracle Database PL/SQL Language Reference for more information about the current user

Sequence LCRs

A sequence LCR is a row LCR that includes information about sequence values. Sequence database objects generate sequence values.

You can stream sequence LCRs in the following ways:

- To capture sequence LCRs using a capture process, set the capture process parameter capture_sequence_nextval to Y.

- To construct sequence LCRs using the OCI interface, use the OCILCRNew function and the OCILCRHeaderSet function with the OCI_ROWLCR_SEQ_LCR flag.

- To construct sequence LCRs using the Java interface, use the DefaultRowLCR constructor and setSequenceLCRFlag method.

An XStream inbound server or an Oracle Streams apply process can use sequence LCRs to ensure that the sequence values at a destination database use the appropriate values. For increasing sequences, the sequence values at the destination are equal to or greater than the sequence values at the source database. For decreasing sequences, the sequence values at the destination are less than or equal to the sequence values at the source database. To instruct an inbound server or apply process to use sequence LCRs, set the apply_sequence_nextval apply parameter to Y.

Note:
Sequence LCRs are intended for one-way replication configurations. Sequence LCRs cannot be used in bi-directional replication configurations.

See Also:

- "Setting a Capture Process Parameter"

- Oracle Database PL/SQL Packages and Types Reference for more information about the capture_sequence_nextval capture process parameter

- Oracle Call Interface Programmer's Guide "OCI XStream Functions" for more information about the OCI interface

- Oracle Database XStream Java API Reference for more information about the Java interface

- Oracle Database Administrator's Guide for information about sequences

Position Order in an LCR Stream

Both XStream Out and XStream In use LCR streams to share transactions. XStream Out sends LCR streams to a client application. XStream In receives LCR streams from a client application.

Each LCR has a position attribute. The position of an LCR identifies its placement in the stream of LCRs in a transaction. Each LCR position has the following properties:

- The position is unique for each LCR.

- The position is of RAW data type.

- The position is strictly increasing within the LCR stream, within a transaction, and across transactions.

- The position is byte-comparable, and the comparison results for multiple positions determines the ordering of the LCRs in the stream.

- The position of an LCR remains identical when the database, the client application, or an XStream component restarts.

- The position is not affected by any rule changes that might reduce or increase the number of LCRs in the stream.

XStream Out only sends committed data, and XStream In only receives committed data.

The following are the properties related to an LCR stream:

- An LCR stream must be repeatable.

- An LCR stream must contain a list of assembled, committed transactions. LCRs from one transaction are contiguous. There is no interleaving of transactions in an LCR stream.

- Each transaction within an LCR stream must have an ordered list of LCRs and a transaction ID.

- The last LCR in each transaction must be a commit LCR.

- Each LCR must have a unique position.

- The position of all LCRs within a single transaction and across transactions must be strictly increasing.

An LCR stream can batch LCRs from multiple transactions and arrange them in increasing position order. LCRs from one transaction are contiguous, and the position must be increasing in the transaction. Also, the position must be nonzero for all LCRs.

See Also:

- "Position of LCRs and XStream Out"

- "Position of LCRs and XStream In"

Rules and Rule Sets

This section describes rules and rule sets.

This section contains the following topics:

- Rules and Rule Sets Defined

- Rule Sets and XStream Components

- System-Created Rules and XStream

See Also:

- "Managing Rules for an XStream Out Configuration"

- "Monitoring XStream Rules"

Rules and Rule Sets Defined

A rule is a database object that enables a client to perform an action when an event occurs and a condition is satisfied. In an XStream configuration, rules identify which LCRs to stream from one component to another. Capture processes, propagations, outbound servers and inbound servers can use rules. You can configure rules for each XStream component independently, and the rules for different XStream components do not need to match.

A rule set is a collection of rules. The behavior of each XStream component is determined by the rules in the rule sets that are associated with it. You can associate a positive rule set and a negative rule set with each XStream component.

In addition, a single rule pertains to either the results of data manipulation language (DML) changes or data definition language (DDL) changes. So, for example, you must use at least two rules to include all of the changes to a particular table: one rule for the results of DML changes and another rule for DDL changes.

The results of a DML change are row changes, and an LCR that encapsulates a row change is called a row LCR. A single DML change can result in multiple row changes. Therefore, a single DML change can result in multiple row LCRs. An LCR that encapsulates a DDL change is called a DDL LCR.

Rule Sets and XStream Components

An XStream component performs its task if a database change satisfies its rule sets. In general, a change satisfies the rule sets when no rules in the negative rule set evaluate to TRUE for the change and at least one rule in the positive rule set evaluates to TRUE for the change. The negative rule set is always evaluated first.

You use rule sets in an XStream configuration to specify the following:

- Changes that a capture process captures from the redo log or discards. If a change found in the redo log satisfies the rule sets for a capture process, then the capture process captures the change. If a change found in the redo log does not satisfy the rule sets for a capture process, then the capture process discards the change.
In XStream Out configurations that share one capture process among several outbound servers, the rules for the capture process must pass the LCRs that are needed by any of the outbound servers that share the capture process.

- The LCRs that a propagation sends from one queue to another or discards. If an LCR in a queue satisfies the rule sets for a propagation, then the propagation sends the LCR. If an LCR in a queue does not satisfy the rule sets for a propagation, then the propagation discards the LCR.

- The LCRs that an outbound server sends to an XStream client application or discards. If an LCR satisfies the rule sets for an outbound server, then the outbound server sends the LCR to the XStream client application. If an LCR does not satisfy the rule sets for an outbound server, then the outbound server discards the LCR.

- The LCRs that an inbound server applies or discards. If an LCR satisfies the rule sets for an inbound server, then the inbound server applies the LCR. If an LCR in not satisfy the rule sets for an inbound server, then the inbound server discards the LCR.

When an XStream component has no rule sets, the component performs its task for all database changes. For example, if an inbound server has no rule sets, then it applies all of the LCRs sent to it by an XStream client application.

System-Created Rules and XStream

An XStream component performs its task for an LCR if the LCR satisfies its rule sets. A system-created rule is created by the DBMS_XSTREAM_ADM package. A system-created rule can specify one of the following levels of granularity: table, schema, or global.

This section describes each of these levels:

- XStream System-Created Rule Procedures

- Global Rules

- Schema Rules

- Table Rules

- Subset Rules

- System-Created Rules and a Multitenant Environment

See Also:

- "Managing Rules for an XStream Out Configuration"

- "Monitoring XStream Rules"

- Oracle Database PL/SQL Packages and Types Reference

XStream System-Created Rule Procedures

Several PL/SQL procedures in the DBMS_XSTREAM_ADM package can create system-generated rules. There are three types of procedures that create system-created rules:

- Procedures that create or alter an outbound server and the rules for the outbound server
These procedures include CREATE_OUTBOUND, ADD_OUTBOUND, and ALTER_OUTBOUND. These procedures make it easy to configure XStream Out quickly. If they meet your needs, then you should use these procedures to simplify XStream Out configuration. The CREATE_OUTBOUND procedure creates the queue and capture process used by the outbound server in addition to the outbound server.

- Procedures that create a propagation or add rules to an existing propagation
These procedures include the ADD_*_PROPAGATION_RULES procedures. If the specified propagation does not exist, then these procedures create the propagation and add rules to the propagation's rule sets. If the specified propagation exists, then these procedures add rules to the existing propagation's rule sets.

- Procedures that add rules to an existing XStream component, such as a capture process, outbound server, or inbound server
These procedures include the ADD_*_RULES procedures. These procedure provide more flexibility and fine-grained control over the system-created rules. You should use these procedures when necessary to add rules to your XStream configuration.

Table 2-6 describes which procedures can create rules for which XStream components.

Table 2-6 XStream System-Created Rule Procedures

Procedure

Capture Process

Propagation

Outbound Server

Inbound Server

CREATE_OUTBOUND

Yes

No

Yes

No

ADD_OUTBOUND

No

No

Yes

No

ALTER_OUTBOUND

Yes

No

Yes

No

ADD_GLOBAL_RULES

Yes

No

Yes

Yes

ADD_GLOBAL_PROPAGATION_RULES

No

Yes

No

No

ADD_SCHEMA_RULES

Yes

No

Yes

Yes

ADD_SCHEMA_PROPAGATION_RULES

No

Yes

No

No

ADD_GLOBAL_RULES

Yes

No

Yes

Yes

ADD_SUBSET_OUTBOUND_RULES

No

No

Yes

No

ADD_SUBSET_RULES

Yes

No

Yes

Yes

ADD_SUBSET_PROPAGATION_RULES

No

Yes

No

No

ADD_TABLE_RULES

Yes

No

Yes

Yes

ADD_TABLE_PROPAGATION_RULES

No

Yes

No

No

See Also:
Oracle Database PL/SQL Packages and Types Reference for detailed information about these procedures

Global Rules

When you use a rule to specify a task that is relevant either to an entire database, you are specifying a global rule. You can specify a global rule for DML changes, a global rule for DDL changes, or a global rule for each type of change (two rules total).

A single global rule in the positive rule set for a capture process means that the capture process captures the results of either all DML changes or all DDL changes to the source database. A single global rule in the negative rule set for a capture process means that the capture process discards the results of either all DML changes or all DDL changes to the source database.

A single global rule in the positive rule set for a propagation means that the propagation rule controls the set of LCRs that are applicable to a specific outbound server. If a single capture services multiple outbound servers, the set of changes distributed to each outbound server is controlled by the propagation rules (the capture rules are the superset of all changes). A single global rule in the negative rule set for a propagation means that the propagation discards either all row LCRs or all DDL LCRs from the capture process.

A single global rule in the positive rule set for an outbound server means that the outbound server sends either all row LCRs or all DDL LCRs that it receives to an XStream client application. A single global rule in the negative rule set for an outbound server means that the outbound server discards either all row LCRs or all DDL LCRs that it receives.

A single global rule in the positive rule set for an inbound server means that the inbound server applies either all row LCRs or all DDL LCRs sent to it by the XStream client application. A single global rule in the negative rule set for an inbound server means that the inbound server discards either all row LCRs or all DDL LCRs sent to it by the XStream client application.

When an inbound server should apply all of the LCRs it receives from its client application, you can configure the inbound server with no rule sets instead of using global rules. Also, for an inbound server to perform best, it should not receive LCRs that it should not apply.

To specify global rules for an outbound server, use the ALTER_OUTBOUND procedure or, for specifying a greater level of detail, the ADD_GLOBAL_RULES procedure in the DBMS_XSTREAM_ADM package.

To specify global rules for an inbound server, use the ALTER_INBOUND procedure or, for specifying a greater level of detail, the ADD_GLOBAL_RULES procedure in the DBMS_XSTREAM_ADM package.

See Also:

- "Managing Rules for an XStream Out Configuration"

- "Monitoring XStream Rules"

- Oracle Database PL/SQL Packages and Types Reference

Schema Rules

When you use a rule to specify a task that is relevant to a schema, you are specifying a schema rule. You can specify a schema rule for DML changes, a schema rule for DDL changes, or a schema rule for each type of change to the schema (two rules total).

A single schema rule in the positive rule set for a capture process means that the capture process captures either the DML changes or the DDL changes to the schema. A single schema rule in the negative rule set for a capture process means that the capture process discards either the DML changes or the DDL changes to the schema.

A single schema rule in the positive rule set for a propagation means that the propagation propagates either the row LCRs or the DDL LCRs in the source queue that contain changes to the schema. A single schema rule in the negative rule set for a propagation means that the propagation discards either the row LCRs or the DDL LCRs in the source queue that contain changes to the schema.

A single schema rule in the positive rule set for an outbound server means that the outbound server sends either the row LCRs or the DDL LCRs that it receives that contain changes to the schema to an XStream client application. A single schema rule in the negative rule set for an outbound server means that the outbound server discards either the row LCRs or the DDL LCRs that it receives that contain changes to the schema.

A single schema rule in the positive rule set for an inbound server means that the inbound server applies either the row LCRs or the DDL LCRs that it receives from an XStream client application that contain changes to the schema. A single schema rule in the negative rule set for an inbound server means that the inbound server discards either the row LCRs or the DDL LCRs that it receives from an XStream client application that contain changes to the schema.

To specify schema rules for either an outbound server or an inbound server, use the ALTER_OUTBOUND procedure or the ADD_SCHEMA_RULES procedure in the DBMS_XSTREAM_ADM package.

See Also:

- "Managing Rules for an XStream Out Configuration"

- "Monitoring XStream Rules"

- Oracle Database PL/SQL Packages and Types Reference

Table Rules

When you use a rule to specify a task that is relevant to a table, you are specifying a table rule. You can specify a table rule for DML changes, a table rule for DDL changes, or a table rule for each type of change to the table (two rules total).

A single table rule in the positive rule set for a capture process means that the capture process captures either the DML changes or the DDL changes to the table. A single table rule in the negative rule set for a capture process means that the capture process discards either the DML changes or the DDL changes to the table.

A single table rule in the positive rule set for a propagation means that the propagation propagates either the row LCRs or the DDL LCRs in the source queue that contain changes to the table. A single table rule in the negative rule set for a propagation means that the propagation discards either the row LCRs or the DDL LCRs in the source queue that contain changes to the table.

A single table rule in the positive rule set for an outbound server means that the outbound server sends either the row LCRs or the DDL LCRs that it receives that contain changes to the table to an XStream client application. A single table rule in the negative rule set for an outbound server means that the outbound server discards either the row LCRs or the DDL LCRs that it receives that contain changes to the table.

A single table rule in the positive rule set for an inbound server means that the inbound server applies either the row LCRs or the DDL LCRs that it receives from an XStream client application that contain changes to the table. A single table rule in the negative rule set for an inbound server means that the inbound server discards either the row LCRs or the DDL LCRs that it receives from an XStream client application that contain changes to the table.

To specify table rules for an outbound server or inbound server, use either the ALTER_OUTBOUND procedure or ADD_TABLE_RULES in the DBMS_XSTREAM_ADM package.

Subset Rules

A subset rule is a special type of table rule for DML changes that is relevant only to a subset of the rows in a table. When you create a subset rule, you use a condition similar to a WHERE clause in a SELECT statement to specify the following:

- That a capture process only captures a subset of the row changes resulting from DML changes to a particular table

- That a propagation only propagates a subset of the row LCRs relating to a particular table

- That an outbound server only sends a subset of the row LCRs relating to a particular table to an XStream client application

- That an inbound server only applies a subset of the row LCRs relating to a particular table

Supplemental logging is required when you specify the following types of subset rules:

- Subset rules for a capture process

- Subset rules for a propagation that will propagate LCRs captured by a capture process

- Subset rules for an outbound server that will send LCRs captured by a capture process to an XStream client application

In any of these cases, an unconditional supplemental log group must be specified at the source database for all the columns in the subset condition. In some cases, when a subset rule is specified, an update can be converted to an insert, and, in these cases, supplemental information might be needed for some or all of the columns.

To specify subset rules for an outbound server, use the ADD_SUBSET_OUTBOUND_RULES, ADD_SUBSET_RULES, or the REMOVE_SUBSET_OUTBOUND_RULES procedures in the DBMS_XSTREAM_ADM package.

See Also:

- "If Required, Configure Supplemental Logging"

- "Adding Subset Rules to an Outbound Server's Positive Rule Set"

- "Removing Subset Rules from an Outbound Server's Positive Rule Set"

- "Monitoring XStream Rules"

- Oracle Database PL/SQL Packages and Types Reference

System-Created Rules and a Multitenant Environment

A multitenant environment enables an Oracle database to contain a portable set of schemas, objects, and related structures that appears logically to an application as a separate database. This self-contained collection is called a pluggable database (PDB). A CDB contains PDBs. This section assumes that you understand multitenant architecture concepts. See Oracle Database Concepts for information.

In a CDB, LCRs can contain the global name of the container where the change originated in the source_database_name attribute and the global name of the root in the root_name attribute. The rules for XStream components can consider these attributes.

The following sections describe how system-generated rules work in XStream Out and XStream In configurations that involve a CDB:

- System-Created Rules in a CDB and XStream Out

- System-Created Rules in a CDB and XStream In

System-Created Rules in a CDB and XStream Out

In a CDB, XStream Out must be configured in the root. Therefore, the PL/SQL procedures in the DBMS_XSTREAM_ADM package that create system-created rules must be run in the root while connected as a common user.

Excluding the procedures that create rules for propagations, the procedures that create system-created rules for XStream Out, such as the ADD_GLOBAL_RULES procedure, include the following key parameters:

Table 2-7 Key Procedure Parameters for System-Created Rules in a CDB

Parameter

Description

source_database

The global name of the source database. In a CDB, specify the global name of the container to which the rules pertain. The container can be the root or a PDB. For example, mycdb.example.com or hrpdb.example.com.

source_root_name

The global name of the root in the source CDB. For example, mycdb.example.com.

source_container_name

The short name of the source container. The container can be the root or a PDB. For example, CDB$ROOT or hrpdb.

If you do not include the domain name when you specify source_database or source_root_name, then the procedure appends it to the name automatically. For example, if you specify DBS1 and the domain is .EXAMPLE.COM, then the procedure specifies DBS1.EXAMPLE.COM automatically.

The combination of these parameters determines which containers' changes XStream Out captures and streams to the client application, based on the rules generated by the procedures. Regardless of the settings for these parameters, system-generated rules can still limit the changes captured and streamed to specific schemas and tables.

Local capture means that a capture process runs on the source CDB. In a local capture configuration, the source_root_name parameter specifies the global name of the root in the local CDB. If this parameter is NULL, then the global name of the root in the local CDB is specified automatically. The resulting rules include a condition for the global name of the root in the current CDB.

Downstream capture means that a capture process runs on a CDB other than the source CDB. In a downstream capture configuration, the source_root_name parameter must be non-NULL, and it must specify the global name of the root in the remote source CDB. The resulting rules include a condition for the global name of the root in the remote CDB. If this parameter is NULL, then local capture is assumed.

Table 2-8 describes the rule conditions for various source_database and source_container_name parameter settings in a local capture configuration.

Table 2-8 Local Capture and XStream Out Container Rule Conditions

source_database Parameter Setting

source_container_name Parameter Setting

Description

NULL

NULL

XStream Out captures and streams changes made in any container in the local CDB, including the root and all PDBs.

non-NULL

NULL

XStream Out captures and streams changes made in the specified source container of the local CDB. The source container can be the root or a PDB. The DBMS_XSTREAM_ADM procedure queries the CDB_PDBS view and CDB_PROPERTIES view to determine the source_container_name value.

NULL

non-NULL

XStream Out captures and streams changes made in the specified source container of the local CDB. The source container can be the root or a PDB. The DBMS_XSTREAM_ADM procedure queries the CDB_PDBS view and CDB_PROPERTIES view to determine the source_database value.

non-NULL

non-NULL

XStream Out captures and streams changes made in the specified source container of the local CDB. The source container can be the root or a PDB.

If the prefix of the source_database value is different from the source_container_name value, then the resulting rules include a condition for the source_database value, and an internal table maps the source_database value to the source_container_name value.

Table 2-9 describes the rule conditions for various source_database and source_container_name parameter settings in a downstream capture configuration.

Table 2-9 Downstream Capture and XStream Out Container Rule Conditions

source_database Parameter Setting

source_container_name Parameter Setting

Description

NULL

NULL

XStream Out captures and streams changes made in any container in the remote source CDB, including the root and all PDBs.

non-NULL

NULL

XStream Out captures and streams changes made in the specified source container of the remote source CDB. The source container can be the root or a PDB. The DBMS_XSTREAM_ADM procedure derives the source_container_name value from the prefix of source_database value.

NULL

non-NULL

The DBMS_XSTREAM_ADM procedure raises an error.

non-NULL

non-NULL

XStream Out captures and streams changes made in the specified source container of the remote source CDB. The source container can be the root or a PDB.

If the prefix of the source_database value is different from the source_container_name value, then the resulting rules include a condition for the source_database value, and an internal table maps the source_database value to the source_container_name value.

See Also:

- "Local Capture and Downstream Capture"

- Oracle Database PL/SQL Packages and Types Reference

System-Created Rules in a CDB and XStream In

Typically, an inbound server does not use rule sets or rules. Instead, it usually processes all of the LCRs that it receives from its client application. You can configure XStream In in the root or in any PDB in a CDB, but the inbound server can apply changes to the current container only. Therefore, if an inbound server is configured in the root, then it can apply changes only to the root. If an inbound server is configured in a PDB, then it can apply changes only to that PDB.

See Also:
Oracle Database Administrator's Guide

Rule-Based Transformations

In XStream, a rule-based transformation is any modification to a logical change record (LCR) when a rule in a positive rule set evaluates to TRUE.

In general, it is best for the client application to perform transformations of the data. If this is not possible, then the database can perform some simple transformations on DML LCRs.

This section contains the following topics:

- Declarative Rule-Based Transformations

- Declarative Rule-Based Transformation Ordering

- Evaluating Transformation Ordering

Declarative Rule-Based Transformations

Declarative rule-based transformations cover a set of common transformation scenarios for row LCRs.

You specify (or declare) such a transformation using one of the following procedures in the DBMS_XSTREAM_ADM package:

- ADD_COLUMN either adds or removes a declarative transformation that adds a column to a row LCR.

- DELETE_COLUMN either adds or removes a declarative transformation that deletes a column from a row LCR.

- KEEP_COLUMNS either adds or removes a declarative transformation that keeps a list of columns in a row LCR. The transformation removes columns that are not in the list from the row LCR.

- RENAME_COLUMN either adds or removes a declarative transformation that renames a column in a row LCR.

- RENAME_SCHEMA either adds or removes a declarative transformation that renames the schema in a row LCR.

- RENAME_TABLE either adds or removes a declarative transformation that renames the table in a row LCR.

When you specify a declarative rule-based transformation, you specify the rule that is associated with it. When the specified rule evaluates to TRUE for a row LCR, XStream performs the declarative transformation internally on the row LCR, without invoking PL/SQL.

Declarative rule-based transformations provide the following advantages:

- Performance is improved because the transformations are run internally without using PL/SQL.

- Complexity is reduced because custom PL/SQL functions are not required.

Declarative rule-based transformations can transform row LCRs only. Therefore, a DML rule must be specified when you run one of the procedures to add a declarative transformation. If a DDL rule is specified, then an error is raised.

Declarative Rule-Based Transformation Ordering

The order in which different types of rule-based transformations is evaluated is important as results will vary.

By default, Oracle Database performs declarative transformations in the following order when the rule evaluates to TRUE:

1. Keep columns

2. Delete column

3. Rename column

4. Add column

5. Rename table

6. Rename schema

The results of a declarative transformation are used in each subsequent declarative transformation. For example, suppose the following declarative transformations are specified for a single rule:

- Delete column address

- Add column address

Assuming column address exists in a row LCR, both declarative transformations should be performed in this case because the column address is deleted from the row LCR before column address is added back to the row LCR. The following table shows the transformation ordering for this example.

Step Number

Transformation Type

Transformation Details

Transformation Performed?

1

Keep columns

-

-

2

Delete column

Delete column address from row LCR

Yes

3

Rename column

-

-

4

Add column

Add column address to row LCR

Yes

5

Rename table

-

-

6

Rename schema

-

-

Another scenario might rename a table and then rename a schema. For example, suppose the following declarative transformations are specified for a single rule:

- Rename table john.customers to sue.clients

- Rename schema sue to mary

Notice that the rename table transformation also renames the schema for the table. In this case, both transformations should be performed and, after both transformations, the table name becomes mary.clients. The following table shows the transformation ordering for this example.

Step Number

Transformation Type

Transformation Details

Transformation Performed?

1

Keep columns

-

-

2

Delete column

-

-

3

Rename column

-

-

4

Add column

-

-

5

Rename table

Rename table john.customers to sue.clients

Yes

6

Rename schema

Rename schema sue to mary

Yes

Consider a similar scenario in which the following declarative transformations are specified for a single rule:

- Rename table john.customers to sue.clients

- Rename schema john to mary

In this case, the first transformation is performed, but the second one is not. After the first transformation, the table name is sue.clients. The second transformation is not performed because the schema of the table is now sue, not john. The following table shows the transformation ordering for this example.

Step Number

Transformation Type

Transformation Details

Transformation Performed?

1

Keep columns

-

-

2

Delete column

-

-

3

Rename column

-

-

4

Add column

-

-

5

Rename table

Rename table john.customers to sue.clients

Yes

6

Rename schema

Rename schema john to mary

No

The rename schema transformation is not performed, but it does not result in an error. In this case, the row LCR is transformed by the rename table transformation, and a row LCR with the table name sue.clients is returned.

Evaluating Transformation Ordering

This section contains information about evaluating transformation ordering.

Row Migration Transformation Ordering

In addition to declarative rule-based transformations, a row migration is an internal transformation that takes place when a subset rule evaluates to TRUE. You can use the DBMS_XSTREAM_ADM.ADD_SUBSET_RULES procedure to add subset rules. If both types of transformations are specified for a single rule, then Oracle Database performs the transformations in the following order when the rule evaluates to TRUE:

1. Row migration

2. Declarative rule-based transformation

User-Specified Declarative Transformation Ordering

If you do not want to use the default declarative rule-based transformation ordering for a particular rule, then you can specify step numbers for each declarative transformation specified for the rule. If you specify a step number for one or more declarative transformations for a particular rule, then the declarative transformations for the rule behave in the following way:

- Declarative transformations are performed in order of increasing step number.

- The default step number for a declarative transformation is 0 (zero). A declarative transformation uses this default if no step number is explicitly specified for it.

- If two or more declarative transformations have the same step number, then these declarative transformations follow the default ordering described in "Declarative Rule-Based Transformation Ordering".

For example, you can reverse the default ordering for declarative transformations by specifying the following step numbers for transformations associated with a particular rule:

- Keep columns with step number 6

- Delete column with step number 5

- Rename column with step number 4

- Add column with step number 3

- Rename table with step number 2

- Rename schema with step number 1

With this ordering specified, rename schema transformations are performed first, and delete column transformations are performed last.

Considerations for Rule-Based Transformations

The following considerations apply to declarative rule-based transformations:

- For a rule-based transformation to be performed by an XStream component, the rule must be in the positive rule set for the XStream component. If the rule is in the negative rule set for the XStream component, then the XStream component ignores the rule-based transformation.

- Rule-based transformations are different from transformations performed using the DBMS_TRANSFORM package. This document does not discuss transformations performed with the DBMS_TRANSFORM package.

- If a large percentage of row LCRs will be transformed in an XStream In configuration, you can use DML handlers with XStream In. Be aware that this method may not perform as well as making the changes in the XStream In client application. If you are performing multiple or complex transformations on row LCRs in an XStream In configuration, then consider reducing the XStream In processing time by making these modifications in the client application prior to sending the changes to XStream In.

XStream and the Oracle Streams Performance Advisor

The Oracle Streams Performance Advisor consists of the DBMS_STREAMS_ADVISOR_ADM PL/SQL package and a collection of data dictionary views. The Performance Advisor enables you to monitor the topology and performance of an XStream environment. The XStream topology includes information about the components in an XStream environment, the links between the components, and the way information flows from capture to consumption. The Performance Advisor also provides information about how Oracle Streams components are performing.

Apply processes function as XStream outbound servers and inbound servers. In general, the Performance Advisor works the same way for an Oracle Streams environment with apply processes and an XStream environment with outbound servers or inbound servers. This section describes important considerations about using the Performance Advisor in an XStream environment.

This section contains these topics:

- XStream Components

- Topology and Stream Paths

- XStream and Component-Level Statistics

- The UTL_SPADV Package

See Also:
Oracle Streams Concepts and Administration for detailed information about using the Oracle Streams Performance Advisor

XStream Components

The Performance Advisor tracks the following types of components in an XStream environment:

- QUEUE

- CAPTURE

- PROPAGATION SENDER

- PROPAGATION RECEIVER

- APPLY

The preceding types are the same in an Oracle Streams environment and an XStream environment, except for APPLY. The APPLY component type can be an XStream outbound server or inbound server.

In addition, the Performance Advisor identifies a bottleneck component as the busiest component or the component with the least amount of idle time. In an XStream configuration, the XStream client application might be the bottleneck when EXTERNAL appears in the ACTION_NAME column of the DBA_STREAMS_TP_PATH_BOTTLENECK view.

XStream Out Apply Subcomponents

The following subcomponent types are possible:

- PROPAGATION SENDER+RECEIVER for sending LCRs from a capture process to an outbound server where the capture process and outbound server are in different databases.

- APPLY READER for a reader server. APPLY READER receives LCRs from the capture process, organizes them into transactions, does dependency calculations, and passes the LCRs to the apply coordinator.

- APPLY COORDINATOR for a coordinator process. It takes the transactions from the capture process, uses the dependency information to determine how to schedule the transactions and sends the LCRs to the apply server.

- APPLY SERVER for an apply server. It delivers the LCRs to the client application.

XStream In Apply Subcomponents

The following subcomponent types are possible:

- APPLY READER for a reader server. It takes the LCRs from client application converts them into transactions, checks the transactional order and does dependency calculations.

- APPLY COORDINATOR for a coordinator process. It takes the transactions from the reader server, uses the dependency information to determine how to schedule the transactions and sends the LCRs to the apply server.

- APPLY SERVER for an apply server. It applies the LCRs to an apply handler. If the LCR cannot be applied, it is placed into an error queue.

Topology and Stream Paths

In the Oracle Streams topology, a stream path is a flow of LCRs from a source to a destination. A stream path begins with a capture process or XStream In client application. A stream path ends where an apply process, outbound server, or inbound server receives the LCRs. The stream path might flow through multiple source and destination components before it reaches an apply process, outbound server, or inbound server. Therefore, a single stream path can consist of multiple source/destination component pairs before it reaches last component.

The Oracle Streams topology only gathers information about a stream path if the stream path ends with an apply process, an outbound server, or an inbound server.

XStream and Component-Level Statistics

The Performance Advisor tracks the following component-level statistics:

- The MESSAGE APPLY RATE is the average number of LCRs applied each second by the apply process, outbound server, or inbound server.

- The TRANSACTION APPLY RATE is the average number of transactions applied by the apply process, outbound server, or inbound server each second. Transactions typically include multiple LCRs.

An LCR can be applied in one of the following ways:

- An apply process or inbound server makes the change encapsulated in the LCR to a database object.

- An apply process or inbound server passes the LCR to an apply handler.

- If the LCR raises an error, then an apply process or inbound server sends the LCR to the error queue.

- An outbound server passes the LCR to an XStream client application. If the LCR raises an error, then the outbound server also reports the error to the client application.

Also, the Performance Advisor tracks the LATENCY component-level statistics. LATENCY is defined in the following ways:

- For apply processes, the LATENCY is the amount of time between when the LCR was created at a source database and when the LCR was applied by the apply process at the destination database.

- For outbound servers, the apply LATENCY is amount of time between when the LCR was created at a source database and when the LCR was sent to the XStream client application.

- For inbound servers, the apply LATENCY is amount of time between when the LCR was created by the XStream client application and when the LCR was applied by the apply process.

When a capture process creates an LCR, the message creation time is the time when the redo entry for the database change was recorded. When an XStream client application creates an LCR, the message creation time is the time when the LCR was constructed.

See Also:
Oracle Streams Concepts and Administration for more information about component-level statistics

The UTL_SPADV Package

The UTL_SPADV package automates the collection of statistics associated with XStream performance. UTL_SPADV provides a series of subprograms that collect and analyze statistics for the XStream components in a distributed database environment. The package uses the Performance Advisor and the COLLECT_STATS procedure to automate the collection of statistics.

The output is formatted so that it can be imported into a spreadsheet easily and analyzed. You can examine XStream performance statistics output with the UTL_SPADV.SHOW_STATS procedure or view the same information in an HTML-formatted report with the UTL_SPADV.SHOW_STATS_HTML procedure.

The UTL_SPADV package works essentially the same way for an Oracle Streams environment with apply processes as it does for an XStream environment with outbound servers or inbound servers. Since XStream is concerned with data changes to or from a client application, the output of the SHOW_STATS procedure is different for XStream than for Oracle Streams.

This section contains the following topics:

- Collecting XStream Statistics Using the UTL_SPADV Package

- Showing XStream Statistics on the Command Line

- Interpreting SHOW_STATS Output

- Showing XStream Statistics in an HTML Report

- Interpreting the HTML Report From SHOW_STATS_HTML

Collecting XStream Statistics Using the UTL_SPADV Package

To collect XStream statistics using the UTL_SPADV package, complete the following steps:

1. Identify the database that you will use to gather the information. An administrative user at this database must meet the following requirements:

- If you want to gather XStream statistics for more than one database, the user must have access to a database link to each database that contains XStream components to monitor.

- The user must have been granted privileges using the DBMS_XSTREAM_AUTH.GRANT_ADMIN_PRIVILEGE procedure. If you want to gather XStream statistics for more than one database, each database link must connect to a user at the remote database that has been granted privileges using the DBMS_XSTREAM_AUTH.GRANT_ADMIN_PRIVILEGE procedure.
If you configure an XStream administrator at each database with XStream components, then the XStream administrator has the necessary privileges.

- The user must have the necessary privileges to create tables and procedures. If you want to gather XStream statistics for more than one database, each database link must connect to a user at the remote database that has the necessary privileges to create tables and procedures.

If no database in your environment meets these requirements, then choose a database, configure the necessary database links, and grant the necessary privileges to the users before proceeding.

2. In SQL*Plus, connect to the database you identified in Step 1 as a user that meets the requirements listed in Step 1.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

3. Run the utlspadv.sql script in the rdbms/admin directory in ORACLE_HOME to load the UTL_SPADV package. For example:

@utlspadv.sql

4. Either collect the current XStream performance statistics once, or create a job that continually monitors XStream performance:

- To collect the current XStream performance statistics once, run the COLLECT_STATS procedure:

exec UTL_SPADV.COLLECT_STATS

This example uses the default values for the parameters in the COLLECT_STATS procedure. Therefore, this example runs the Performance Advisor 10 times with 60 seconds between each run. These values correspond with the default values for the num_runs and interval parameters, respectively, in the COLLECT_STATS procedure.

- To create a job that continually monitors XStream performance:

exec UTL_SPADV.START_MONITORING

This example creates a monitoring job, and the monitoring job gathers performance statistics continually at set intervals. This example uses the default values for the parameters in the START_MONITORING procedure. Therefore, this example runs the Performance Advisor every 60 seconds. This value corresponds with the default value for the interval parameter in the START_MONITORING procedure. If an interval is specified in the START_MONITORING procedure, then the specified interval is used for the interval parameter in the COLLECT_STATS procedure.

These procedures include several parameters that you can use to adjust the way performance statistics are gathered. See Oracle Database PL/SQL Packages and Types Reference for more information.

You can show the statistics by running the SHOW_STATS procedure. See "Showing XStream Statistics on the Command Line".

See Also:
Oracle Database PL/SQL Packages and Types Reference for more information about the UTL_SPADV package

Showing XStream Statistics on the Command Line

The SHOW_STATS procedure in the UTL_SPADV package displays the statistics that the Performance Advisor gathered and stored. Use the path_stat_table parameter to specify the table that contains the statistics.

When you gather statistics using the COLLECT_STATS procedure, this table is specified in the path_stat_table parameter in the COLLECT_STATS procedure. By default, the table name is STREAMS$_ADVISOR_PATH_STAT.

When you gather statistics using the START_MONITORING procedure, you can determine the name for this table by querying the SHOW_STATS_TABLE column in the STREAMS$_PA_MONITORING view. The default table for a monitoring job is STREAMS$_PA_SHOW_PATH_STAT.

To show statistics collected using the UTL_SPADV package and stored in the STREAMS$_ADVISOR_PATH_STAT table, complete the following steps:

1. Collect statistics by completing the steps described in "Collecting XStream Statistics Using the UTL_SPADV Package".

2. Connect to the database as the user who collected the statistics.

3. If you are using a monitoring job, then query the SHOW_STATS_TABLE column in the STREAMS$_PA_MONITORING view to determine the name of this table that stores the statistics:

SELECT SHOW_STATS_TABLE FROM STREAMS$_PA_MONITORING;

4. Run the SHOW_STATS procedure.
For example, if you are using a monitoring job and the default storage table, then run the following procedure:

SET SERVEROUTPUT ON SIZE 50000
BEGIN
UTL_SPADV.SHOW_STATS(
path_stat_table => 'STREAMS$_PA_SHOW_PATH_STAT');
END;
/

Interpreting SHOW_STATS Output

This section describes the differences between the output for apply processes and the output for XStream outbound servers and inbound servers.

Note:
The rest of this section assumes that you are familiar with the UTL_SPADV package and the SHOW_STATS output for apply processes. See Oracle Streams Concepts and Administration and Oracle Database PL/SQL Packages and Types Reference for detailed information about using the UTL_SPADV package.

The following sections describe the output for the SHOW_STATS procedure for outbound servers and inbound servers:

- Sample Output When an Outbound Server Is the Last Component in a Path

- Sample Output When an Inbound Server Is the Last Component in a Path

Sample Output When an Outbound Server Is the Last Component in a Path

The following is sample output for when an outbound server is the last component in a path:

LEGEND
<statistics>=<capture>  [<queue>  <psender>  <preceiver>  <queue>  ]<apply>
<bottleneck>
<capture>    = '|<C>'<name>  <msgs captured/sec>  <msgs enqueued/sec>  <latency>
'LMR'<idl%>  <flwctrl%>  <topevt%>  <topevt>
'LMP' (<parallelism>)<idl%>  <flwctrl%>  <topevt%>  <topevt>
'LMB'<idl%>  <flwctrl%>  <topevt%>  <topevt>
'CAP'<idl%>  <flwctrl%>  <topevt%>  <topevt>
'CAP+PS'<msgs sent/sec>  <bytes sent/sec>  <latency>  <idl%>
<flwctrl%>  <topevt%>  <topevt>
<apply>      = '|<A>'<name>  <msgs applied/sec>  <txns applied/sec>  <latency>
'PS+PR'<idl%>  <flwctrl%>  <topevt%>  <topevt>
'APR'<idl%>  <flwctrl%>  <topevt%>  <topevt>
'APC'<idl%>  <flwctrl%>  <topevt%>  <topevt>
'APS' (<parallelism>)<idl%>  <flwctrl%>  <topevt%>  <topevt>
<queue>      = '|<Q>'<name>  <msgs enqueued/sec>  <msgs spilled/sec>  <msgs in
queue>
<psender>    = '|<PS>'<name>  <msgs sent/sec>  <bytes sent/sec>  <latency>  <idl%>
<flwctrl%>  <topevt%>  <topevt>
<preceiver>  = '|<PR>'<name>  <idl%>  <flwctrl%>  <topevt%>  <topevt>
<bottleneck>= '|<B>'<name>  <sub_name>  <sessionid>  <serial#>  <topevt%>  <topevt>

OUTPUT
PATH 1 RUN_ID 2 RUN_TIME 2009-MAY-15 12:20:55 CCA Y
|<C> CAP$_XOUT_1 2733 2730 3392 LMR 8.3% 91.7% 0% "" LMP (1) 8.3% 91.7% 0% ""
LMB 8.3% 91.7% 0% "" CAP 8.3% 91.7% 0% "" |<Q> "XSTRMADMIN"."Q$_XOUT_2" 2730 0.01
4109 |<A> XOUT 2329 2.73 0 -1 PS+PR 8.3% 91.7% 0% "" APR 8.3% 91.7% 0% "" APC
100% 0% 0% "" APS (1) 8.3% 83.3% 8.3% "" |<B> "EXTERNAL"
.
.
.

Note:
This output is for illustrative purposes only. Actual performance characteristics vary depending on individual configurations and conditions.

In this output, the A component is the outbound server XOUT. The output for when an outbound server is the last component in a path is similar to the output for when an apply process is the last component in a path. However, the apply server (APS) is not the last component because the outbound server connects to a client application. Statistics are not collected for the client application.

In an XStream Out configuration, the output can indicate flow control for the network because the "SQL*Net more data to client" performance metric for an apply server is measured like a flow control event. If the output indicates flow control for an apply server, then either the network or the client application is considered the bottleneck component. In the previous output, EXTERNAL indicates that either the network or the client application is the bottleneck.

Other than these differences, you can interpret the statistics in the same way that you would for a path that ends with an apply process. Use the legend and the abbreviations to determine the statistics in the output.

Sample Output When an Inbound Server Is the Last Component in a Path

The following is sample output for when an inbound server is the last component in a path:

OUTPUT
PATH 1 RUN_ID 2 RUN_TIME 2009-MAY-16 10:11:38 CCA N
|<PR> "clientcap"=> 75% 0% 8.3% "CPU + Wait for CPU" |<Q> "XSTRMADMIN"."QUEUE2"  467 0.01 1
|<A> XIN 476 4.71 0 APR 100% 0% 0% "" APC 100% 0% 0% "" APS (4) 366.7% 0% 33.3% "CPU + Wait for CPU"
|<B> "EXTERNAL"
.
.
.

Note:
This output is for illustrative purposes only. Actual performance characteristics vary depending on individual configurations and conditions.

In this output, the A component is the inbound server XIN. When an inbound server is the last component in a path, the XStream client application connects to the inbound server, and the inbound server applies the changes in the LCRs. The client application is not shown in the output.

The propagation receiver receives the LCRs from the client application. So, the propagation receiver is the first component shown in the output. In the previous sample output, the propagation receiver is named clientcap. In this case, clientcap is the source name given by the client application when it attaches to the inbound server.

If the propagation receiver is idle for a significant percentage of time, then either the network or the client application is considered a bottleneck component. In the previous output, EXTERNAL indicates that either the network or the client application is the bottleneck.

Other than these differences, you can interpret the statistics in the same way that you would for a path that ends with an apply process. If you and the abbreviations to determine the statistics in the output.

Showing XStream Statistics in an HTML Report

The SHOW_STATS_HTML procedure in the UTL_SPADV package creates an HTML report that contains the statistics that the Performance Advisor gathered and stored. Use the comp_stat_table parameter to specify the table that contains the statistics.

When you gather statistics using the COLLECT_STATS procedure, this table is specified in the comp_stat_table parameter in the COLLECT_STATS procedure. By default, the table name is STREAMS$_ADVISOR_COMP_STAT.

When you gather statistics using the START_MONITORING procedure, you can determine the name for this table by querying the SHOW_STATS_TABLE column in the STREAMS$_PA_MONITORING view. The default table for a monitoring job is STREAMS$_ADVISOR_COMP_STAT.

The default for the comp_stat_table parameter is STREAMS$_ADVISOR_COMP_STAT. Ensure that you specify the correct table when you run the SHOW_STATS_HTML procedure.

The SHOW_STATS_HTML procedure must store the HTML report in a directory. Use the directory parameter to specify a directory object.

To show statistics collected using the UTL_SPADV package and stored in the STREAMS$_ADVISOR_COMP_STAT table, complete the following steps:

1. Collect statistics by completing the steps described in "Collecting XStream Statistics Using the UTL_SPADV Package".

2. Connect to the database as the user who collected the statistics.

3. If you are using a monitoring job, then query the SHOW_STATS_TABLE column in the STREAMS$_PA_MONITORING view to determine the name of this table that stores the statistics:

SELECT SHOW_STATS_TABLE FROM STREAMS$_PA_MONITORING;

4. Create a directory object for the directory that will contain the files in the HTML report.
For example, to create a directory object named XSTREAM_STATS_HTML for the /usr/xstream/reports directory, run the following SQL statement:

CREATE DIRECTORY XSTREAM_STATS_HTML AS '/usr/xstream/reports';

5. Run the SHOW_STATS_HTML procedure.
For example, if you are using a monitoring job and the default storage table, then run the following procedure:

BEGIN
UTL_SPADV.SHOW_STATS_HTML(
directory       => 'XSTREAM_STATS_HTML',
reportname      => 'xstream_stats.html',
comp_stat_table => 'STREAMS$_ADVISOR_COMP_STAT');
END;
/

Interpreting the HTML Report From SHOW_STATS_HTML

The SHOW_STATS_HTML procedure in the UTL_SPADV package can generate the same output as the SHOW_STATS procedure, but it formats the output as HTML in HTML files. The SHOW_STATS_HTML output is easier to read than the SHOW_STATS output. For example, the procedure generates multiple files, and each file begins with the report name. The report includes tables with the performance statistics. Statistics for different paths are in different rows in these tables, and you can click on a path for more detailed statistics about the path. The report_name parameter indicates the master HTML file with links to the other HTML files.

The following are considerations for using the SHOW_STATS_HTML procedure:

- The default table that stores the statistics is STREAMS$_ADVISOR_COMP_STAT. The SHOW_STATS procedure uses a different default table (STREAMS$_ADVISOR_PATH_STAT).

- You must specify a directory object in the directory parameter of the procedure. This directory stores the HTML files generated by the procedure.
The specified directory object must be created using the SQL statement CREATE DIRECTORY, and the user who invokes the procedure must have READ and WRITE privilege on the directory.

Figure 2-1 shows a portion of an HTML report generated by the SHOW_STATS_HTML procedure.

Figure 2-1 HTML Report Generated by the SHOW_STATS_HTML Procedure

See Also:
"Interpreting SHOW_STATS Output"

XStream and SQL Generation

SQL generation is the ability to generate the SQL statement required to perform the change encapsulated in a row LCR. XStream outbound servers and XStream inbound servers can use SQL generation to generate the SQL statement necessary to perform the insert, update, or delete operation in a row LCR.

This section contains these topics:

- Interfaces for Performing SQL Generation

- SQL Generation Formats

- SQL Generation and Data Types

- SQL Generation and Character Sets

- Sample Generated SQL Statements

- SQL Generation Demo

Interfaces for Performing SQL Generation

You can use the following interfaces to perform SQL generation:

- The PL/SQL interface, which uses the GET_ROW_TEXT and GET_WHERE_CLAUSE member procedures for row LCRs

- The OCI for XStream

- The Java interface for XStream

The PL/SQL interface generates SQL in a CLOB data type, while the OCI and Java interfaces generate SQL in plain text. In the Java interface, the size of the text is limited by the size of String data type.

See Also:

- Oracle Database PL/SQL Packages and Types Reference for information about the GET_ROW_TEXT and GET_WHERE_CLAUSE row LCR member procedures

- Oracle Call Interface Programmer's Guide

- Oracle Database XStream Java API Reference for information about the Java interface for XStream

SQL Generation Formats

SQL statements can be generated in one of two formats: inline values or bind variables. Use inline values when the returned SQL statement is relatively small. For larger SQL statements, use bind variables. In this case, the bind variables are passed to the client application in a separate list that includes pointers to both old and new column values.

For information about using bind variables with each interface, refer to the following documentation:

- The documentation for the GET_ROW_TEXT and GET_WHERE_CLAUSE row LCR member procedures in Oracle Database PL/SQL Packages and Types Reference

- Oracle Call Interface Programmer's Guide "OCILCRRowStmtWithBindVarGet()"

- The documentation for DefaultRowLCR.getBinds() in Oracle Database XStream Java API Reference

Note:
For generated SQL statements with the values inline, SQL injection is possible. SQL injection is a technique for maliciously exploiting applications that use client-supplied data in SQL statements, thereby gaining unauthorized access to a database to view or manipulate restricted data. Oracle strongly recommends using bind variables if you plan to execute the generated SQL statement. See Oracle Database PL/SQL Language Reference for more information about SQL injection.

See Also:
Oracle Streams Concepts and Administration for an example that uses the GET_ROW_TEXT procedure for SQL generation

SQL Generation and Data Types

SQL generation supports the following data types:

- VARCHAR2

- NVARCHAR2

- NUMBER

- FLOAT

- DATE

- BINARY_FLOAT

- BINARY_DOUBLE

- LONG

- TIMESTAMP

- TIMESTAMP WITH TIME ZONE

- TIMESTAMP WITH LOCAL TIME ZONE

- INTERVAL YEAR TO MONTH

- INTERVAL DAY TO SECOND

- RAW

- LONG RAW

- CHAR

- NCHAR

- CLOB with BASICFILE storage

- NCLOB with BASICFILE storage

- BLOB with BASICFILE storage

- XMLType stored as CLOB, object relational, or as binary XML

Note:

- The maximum size of the VARCHAR2, NVARCHAR2, and RAW data types has been increased in Oracle Database 12c when the COMPATIBLE initialization parameter is set to 12.0.0 and the MAX_STRING_SIZE initialization parameter is set to EXTENDED.

- XMLType stored as a CLOB is deprecated in this release.

See Also:
Oracle Database SQL Language Reference for information about data types

SQL Generation and Automatic Data Type Conversion

An XStream outbound server or inbound server performs implicit data type conversion where it is possible, and the generated SQL follows ANSI standards where it is possible. The following are considerations for automatic data type conversions:

- NULL is specified as "NULL".

- Single quotation marks are converted into double quotation marks for the following data types when they are inline values: CHAR, VARCHAR2, NVARCHAR2, NCHAR, CLOB, and NCLOB.

- LONG data is converted into CLOB data.

- LONG RAW data is converted into BLOB data.

SQL Generation and LOB, LONG, LONG RAW, and XMLType Data Types

For INSERT and UPDATE operations on LOB columns, an outbound server automatically assembles the LOB chunks using LOB assembly. For these operations, the generated SQL includes a non-NULL empty value. The actual values of the chunked columns arrive in subsequent LCRs. For each chunk, you must perform the correct SQL operation on the correct column.

Similarly, for LONG, LONG RAW, and XMLType data types, an outbound server generates a non-NULL empty value, and the actual values of the column arrive in chunks in subsequent LCRs. For each chunk, you must perform the correct SQL operation on the correct column.

In the inline version of the generated SQL, for LOB, LONG, LONG RAW, and XMLType data type columns, the following SQL is generated for inserts and updates:

- For CLOB, NCLOB, and LONG data type columns:

EMPTY_CLOB()

- For BLOB and LONG RAW data type columns:

EMPTY_BLOB()

- For XMLType columns:

XMLTYPE.CREATEXML('xml /')

where xml / is the XML chunk.

After the LCR that contains the DML statement arrives, the data for these changes arrive in separate chunks. You can generate the WHERE clause for such a change and use the generated WHERE clause to identify the row for the modifications contained in the chunks. For example, in PL/SQL you can use the GET_WHERE_CLAUSE row LCR member procedure to generate the WHERE clause for a row change.

For INSERT and UPDATE operations, the generated WHERE clause identifies the row after the insert or update. For example, consider the following update to the hr.departments table:

UPDATE hr.departments SET department_name='Management'
WHERE department_name='Administration';

The generated WHERE clause for this change is the following:

WHERE "DEPARTMENT_NAME"='Management'

For piecewise LOB operation performed by subprograms in the DBMS_LOB package (including the WRITE, TRIM, and ERASE procedures), the generated SQL includes a SELECT FOR UPDATE statement.

For example, a LOB_WRITE operation on a clob_col results in generated SQL similar to the following:

SELECT "CLOB_COL" FROM "HR"."LOB_TAB" WHERE "N1"=2 FOR UPDATE

The selected clob_col must be defined. You can use the LOB locator to perform piecewise LOB operations with the LOB chunks that follow the row LCR.

See Also:

- "Sample Generated SQL Statements"

- Oracle Streams Replication Administrator's Guide for information about LOB assembly

SQL Generation and Character Sets

When you use the LCR methods, the generated SQL is in the database character set. SQL keywords, such as INSERT, UPDATE, and INTO, do not change with the character set.

See Also:

- Oracle Database Globalization Support Guide for information about data conversion in JDBC

- Oracle Database SQL Language Reference for information about SQL keywords

Sample Generated SQL Statements

This section provides examples of generated SQL statements:

- Sample Generated SQL Statements for the hr.employees Table

- Sample Generated SQL Statements for a Table With LOB Columns

Sample Generated SQL Statements for the hr.employees Table

This section provides examples of SQL statements generated by an outbound server for changes made to the hr.employees table.

This section includes these examples:

- Example 2-1, "Generated Insert"

- Example 2-2, "Generated Update"

- Example 2-3, "Generated Delete"

Note:
Generated SQL is in a single line and is not formatted.

Example 2-1 Generated Insert

Assume the following insert is executed:

INSERT INTO hr.employees (employee_id,
last_name,
email,
hire_date,
job_id,
salary,
commission_pct)
VALUES (207,
'Gregory',
'pgregory@example.com',
SYSDATE,
'PU_CLERK',
9000,
NULL);

The following is the generated SQL with inline values:

INSERT INTO "HR"."EMPLOYEES"("EMPLOYEE_ID","FIRST_NAME","LAST_NAME",
"EMAIL","PHONE_NUMBER","HIRE_DATE","JOB_ID","SALARY","COMMISSION_PCT",
"MANAGER_ID","DEPARTMENT_ID" ) VALUES ( 207, NULL,'Gregory',
'pgregory@example.com', NULL , TO_DATE(' 2009-04-15','syyyy-mm-dd'),
'PU_CLERK',9000, NULL , NULL , NULL )

The following is the generated SQL with bind variables:

INSERT INTO "HR"."EMPLOYEES"("EMPLOYEE_ID","FIRST_NAME","LAST_NAME",
"EMAIL","PHONE_NUMBER","HIRE_DATE","JOB_ID","SALARY",
"COMMISSION_PCT","MANAGER_ID","DEPARTMENT_ID" ) VALUES ( :1   ,:2   ,:3
,:4   ,:5   ,:6   ,:7   ,:8   ,:9   ,:10  ,:11  )

Example 2-2 Generated Update

Assume the following update is executed:

UPDATE hr.employees SET salary=10000 WHERE employee_id=207;

The following is the generated SQL with inline values:

UPDATE "HR"."EMPLOYEES" SET "SALARY"=10000 WHERE "EMPLOYEE_ID"=207
AND "SALARY"=9000

The following is the generated SQL with bind variables:

UPDATE "HR"."EMPLOYEES" SET "SALARY"=:1    WHERE "EMPLOYEE_ID"=:2
AND "SALARY"=:3

Example 2-3 Generated Delete

Assume the following delete is executed:

DELETE FROM hr.employees WHERE employee_id=207;

The following is the generated SQL with inline values:

DELETE  FROM "HR"."EMPLOYEES" WHERE "EMPLOYEE_ID"=207 AND "FIRST_NAME" IS NULL
AND "LAST_NAME"='Gregory' AND "EMAIL"='pgregory@example.com' AND
"PHONE_NUMBER" IS NULL  AND "HIRE_DATE"= TO_DATE(' 2009-04-15','syyyy-mm-dd')
AND "JOB_ID"='PU_CLERK' AND "SALARY"=10000 AND "COMMISSION_PCT" IS NULL
AND "MANAGER_ID" IS NULL  AND "DEPARTMENT_ID" IS NULL

The following is the generated SQL with bind variables:

DELETE  FROM "HR"."EMPLOYEES" WHERE "EMPLOYEE_ID"=:1    AND "FIRST_NAME"=:2
AND "LAST_NAME"=:3    AND "EMAIL"=:4    AND "PHONE_NUMBER"=:5    AND
"HIRE_DATE"=:6    AND "JOB_ID"=:7    AND "SALARY"=:8    AND
"COMMISSION_PCT"=:9   AND "MANAGER_ID"=:10   AND "DEPARTMENT_ID"=:11

Sample Generated SQL Statements for a Table With LOB Columns

This section provides examples of SQL statements generated by an outbound server for changes made to the following table:

CREATE TABLE hr.lob_tab(
n1        number primary key,
clob_col  CLOB,
nclob_col NCLOB,
blob_col  BLOB);

This section includes these examples:

- Example 2-4, "Generated Insert for a Table with LOB Columns"

- Example 2-5, "Generated Update for a Table with LOB Columns"

- Example 2-6, "Generated Delete for a Table with LOB Columns"

Note:
Generated SQL is in a single line and is not formatted.

Example 2-4 Generated Insert for a Table with LOB Columns

Assume the following insert is executed:

INSERT INTO hr.lob_tab VALUES (2, 'test insert', NULL, NULL);

The following is the generated SQL with inline values:

INSERT INTO "HR"."LOB_TAB"("N1","BLOB_COL","CLOB_COL","NCLOB_COL" )
VALUES ( 2,, EMPTY_CLOB() ,)

The following is the generated SQL with bind variables:

INSERT INTO "HR"."LOB_TAB"("N1","BLOB_COL","CLOB_COL","NCLOB_COL" )
VALUES ( :1   ,:2   ,:3   ,:4   )

The GET_WHERE_CLAUSE member procedure generates the following WHERE clause for this insert:

- Inline:

WHERE "N1"=2

- Bind variables:

WHERE "N1"=:1

You can use the WHERE clause to identify the row that was inserted when the subsequent chunks arrive for the LOB column change.

Example 2-5 Generated Update for a Table with LOB Columns

Assume the following update is executed:

UPDATE hr.lob_tab SET clob_col='test update' WHERE n1=2;

The following is the generated SQL with inline values:

UPDATE "HR"."LOB_TAB" SET "CLOB_COL"= EMPTY_CLOB()  WHERE "N1"=2

The following is the generated SQL with bind variables:

UPDATE "HR"."LOB_TAB" SET "CLOB_COL"=:1    WHERE "N1"=:2

Example 2-6 Generated Delete for a Table with LOB Columns

Assume the following delete is executed:

DELETE FROM hr.lob_tab WHERE n1=2;

The following is the generated SQL with inline values:

DELETE  FROM "HR"."LOB_TAB" WHERE "N1"=2

The following is the generated SQL with bind variables:

DELETE  FROM "HR"."LOB_TAB" WHERE "N1"=:1

SQL Generation Demo

A demo that performs SQL generation is available. The demo uses the DBMS_XSTREAM_ADM PL/SQL package to configure an XStream Out environment, and it uses an OCI client application to perform SQL generation.

The demo uses SQL generation to replicate DML changes from a source database to a destination database. Specifically, the demo creates the xsdemosg schema in both the source database and the destination database. It creates various types of tables in the xsdemosg schema at each database, including tables with LOB columns. It executes a set of DML statements on the tables in xsdemosg schema in the source database. Oracle Streams components, such as a capture process and a queue, send the changes in the form of LCRs to an XStream outbound server that is also running on the source database. The outbound server makes the LCRs available to the demo client application.

The demo client application, when run, uses the OCI API to connect to the outbound server and receive the LCRs. The demo client application uses SQL generation to execute the changes that are encapsulated in the LCRs. Therefore, the client application replicates the changes made to xsdemosg schema in the source database to the xsdemosg in the destination database.

You can modify the demo to replicate changes to any schema. Both the schema and the replicated tables must exist on both the source database and the destination database. SQL generation is only possible for DML changes. Therefore, this demo cannot be used to replicate DDL changes.

This demo is available in the following location:

$ORACLE_HOME/rdbms/demo/xstream/sqlgen

Note:
The SQL generation demo is not available for the XStream Java API.

Part II

XStream Out

This part describes XStream Out. This part contains the following chapters:

- Chapter 3, "XStream Out Concepts"

- Chapter 4, "Configuring XStream Out,"

- Chapter 5, "Managing XStream Out,"

- Chapter 6, "Monitoring XStream Out,"

- Chapter 7, "Troubleshooting XStream Out,"

3 XStream Out Concepts

This chapter contains concepts related to XStream Out.

This chapter contains these topics:

- Introduction to XStream Out

- Capture Processes

- Outbound Servers

- Position of LCRs and XStream Out

- XStream Out and Distributed Transactions

- XStream Out and Security

- XStream Out and Other Oracle Database Components

See Also:
Chapter 4, "Configuring XStream Out"

Introduction to XStream Out

XStream Out can capture transactions from the redo log of an Oracle database and send them efficiently to a client application. XStream Out provides a transaction-based interface for streaming these changes to client applications. The client application can interact with other systems, including non-Oracle systems, such as non-Oracle databases or file systems.

In an XStream Out configuration, a capture process captures database changes and sends these changes to an outbound server. This section describes capture processes and outbound servers in detail.

XStream Out has both OCI and Java interfaces and supports most of the data types that are supported by Oracle Database, including LOBs, LONG, LONG RAW, and XMLType.

This section contains these topics:

- Outbound Servers

- ID Key LCRs

- Considerations for Outbound Servers

- XStream Out and Distributed Transactions

See Also:

- Oracle Call Interface Programmer's Guide

- Oracle Database XStream Java API Reference

Capture Processes

This section describes capture processes. This section contains the following topics:

- Capture Process Overview

- Data Types Captured by a Capture Process

- Types of DML Changes Captured by Capture Processes

- Local Capture and Downstream Capture

- SCN Values Related to a Capture Process

- Capture Processes and RESTRICTED SESSION

- Capture Process Subcomponents

- Privileges Required by the Capture User for a Capture Process

- Capture Process States

- Capture Process Parameters

- Capture Process Checkpoints and XStream Out

Capture Process Overview

A capture process is an optional Oracle background process that scans the database redo log to capture DML and DDL changes made to database objects. The primary function of the redo log is to record all of the changes made to the database. A capture process captures database changes from the redo log, and the database where the changes were generated is called the source database for the capture process.

When a capture process captures a database change, it converts it into a specific message format called a logical change record (LCR). In an XStream Out configuration, the capture process sends these LCRs to an outbound server.

Figure 3-1 shows a capture process.

Figure 3-1 Capture Process

A capture process can run on its source database or on a remote database. When a capture process runs on its source database, the capture process is a local capture process.

You can also capture changes for the source database by running the capture process on different server. When a capture process runs on a remote database, the capture process is called a downstream capture process, and the remote database is called the downstream database. The log files are written to the remote database and to the source database. In this configuration, the source logfiles must be available at the downstream capture database. The capture process on the remote database mines the logs from the source database and stages them locally. This configuration can be helpful when you want to offload the processing of capture changes from a production database to different, remote database.

Data Types Captured by a Capture Process

When capturing the row changes resulting from DML changes made to tables, a capture process can capture changes made to columns of the following data types:

- VARCHAR2

- NVARCHAR2

- NUMBER

- FLOAT

- LONG

- DATE

- BINARY_FLOAT

- BINARY_DOUBLE

- TIMESTAMP

- TIMESTAMP WITH TIME ZONE

- TIMESTAMP WITH LOCAL TIME ZONE

- INTERVAL YEAR TO MONTH

- INTERVAL DAY TO SECOND

- RAW

- LONG RAW

- UROWID

- CHAR

- NCHAR

- CLOB with BASICFILE or SECUREFILE storage

- NCLOB with BASICFILE or SECUREFILE storage

- BLOB with BASICFILE or SECUREFILE storage

- XMLType stored as CLOB, object relational, or as binary XML

- Object types

- The following Oracle-supplied types: ANYDATA, SDO_GEOMETRY, and media types

If XStream is replicating data for an object type, then the replication must be unidirectional, and all replication sites must agree on the names and data types of the attributes in the object type. You establish the names and data types of the attributes when you create the object type. For example, consider the following object type:

CREATE TYPE cust_address_typ AS OBJECT
(street_address     VARCHAR2(40),
postal_code        VARCHAR2(10),
city               VARCHAR2(30),
state_province     VARCHAR2(10),
country_id         CHAR(2));
/

At all replication sites, street_address must be VARCHAR2(40), postal_code must be VARCHAR2(10), city must be VARCHAR2(30), and so on.

Note:

- The maximum size of the VARCHAR2, NVARCHAR2, and RAW data types has been increased in Oracle Database 12c when the COMPATIBLE initialization parameter is set to 12.0.0 and the MAX_STRING_SIZE initialization parameter is set to EXTENDED.

- Varrays are not supported, but object type attributes can include varrays.

- XMLType stored as a CLOB is deprecated in this release.

See Also:
Oracle Database SQL Language Reference for information about data types

ID Key LCRs

XStream Out does not fully support the following data types in row LCRs:

- BFILE

- ROWID

- The following user-defined types: varrays, REFs, and nested tables

- The following Oracle-supplied types: ANYTYPE, ANYDATASET, URI types, SDO_TOPO_GEOMETRY, SDO_GEORASTER, and Expression.

These data type restrictions pertain to both ordinary (heap-organized) tables and index-organized tables.

An ID key LCR is a special type of row LCR. ID key LCRs enable an XStream client application to process changes to rows that include unsupported data types. ID key LCRs do not contain all of the columns for a row change. Instead, they contain the rowid of the changed row, a group of key columns to identify the row in the table, and the data for the scalar columns of the table that are supported by XStream Out. ID key LCRs do not contain data for columns of unsupported data types.

XStream Out can capture changes for tables that are not fully supported by setting the CAPTURE_IDKEY_OBJECTS capture process parameter to Y. An XStream client application can use ID key LCRs in the following ways:

- If the application does not require the data in the unsupported columns, then the application can process the values of the supported columns in the ID key LCRs normally.

- If the application requires the data in the unsupported columns, then the application can use the information in an ID key LCR to query the correct row in the database and consume the unsupported data for the row.

You can use the DBA_XSTREAM_OUT_SUPPORT_MODE view to display a list of local tables supported by ID key LCRs. This view shows the following types of XStream Out support for tables in the SUPPORT_MODE column:

- FULL for tables that are fully supported by XStream Out (without using ID key LCRs)

- ID KEY for tables that are supported only by using ID key LCRs

- NONE for tables that are not supported by XStream Out.
Even ID key LCRs cannot be used to process changes to rows in tables that show NONE in the DBA_XSTREAM_OUT_SUPPORT_MODE view.

For example, run the following query to show XStream Out support for all of the tables in the database:

COLUMN OWNER FORMAT A30
COLUMN OBJECT_NAME FORMAT A30
COLUMN SUPPORT_MODE FORMAT A12

SELECT OWNER, OBJECT_NAME, SUPPORT_MODE
FROM DBA_XSTREAM_OUT_SUPPORT_MODE
ORDER BY OBJECT_NAME;

Your output is similar to the following:

OWNER                          OBJECT_NAME                    SUPPORT_MODE
------------------------------ ------------------------------ ------------
.
.
.

IX                             ORDERS_QUEUETABLE              NONE
OE                             ORDER_ITEMS                    FULL
SH                             PLAN_TABLE                     FULL
PM                             PRINT_MEDIA                    ID KEY
.
.
.

See Also:

- Oracle Database Reference

- "Row LCRs"

- "Setting a Capture Process Parameter"

ID Key LCRs Demo

A demo is available that creates a sample client application that process ID key LCRs. Specifically, the client application attaches to an XStream outbound server and waits for LCRs from the outbound server. When the client application receives an ID key LCR, it can query the appropriate source database table using the rowid in the ID key LCR.

The demo is available in the following location in both OCI and Java code:

$ORACLE_HOME/rdbms/demo/xstream/idkey

Types of DML Changes Captured by Capture Processes

When you specify that DML changes made to certain tables should be captured, a capture process captures the following types of DML changes made to these tables:

- INSERT

- UPDATE

- DELETE

- MERGE

- Piecewise operations

A capture process converts each MERGE change into an INSERT or UPDATE change. MERGE is not a valid command type in a row LCR.

Local Capture and Downstream Capture

You can configure a capture process to run locally on a source database or remotely on a downstream database. A single database can have one or more capture processes that capture local changes and other capture processes that capture changes from a remote source database. That is, you can configure a single database to perform both local capture and downstream capture.

Local Capture

Local capture means that a capture process runs on the source database. Figure 3-1 shows a database using local capture.

The Source Database Performs All Change Capture Actions

If you configure local capture, then the following actions are performed at the source database:

- The DBMS_CAPTURE_ADM.BUILD procedure is run to extract (or build) the data dictionary to the redo log.

- Supplemental logging at the source database places additional information in the redo log. This information might be needed when captured changes are processed by an XStream client application. See "If Required, Configure Supplemental Logging".

- The first time a capture process is started at the database, Oracle Database uses the extracted data dictionary information in the redo log to create a LogMiner data dictionary, which is separate from the primary data dictionary for the source database. Additional capture processes can use this existing LogMiner data dictionary, or they can create new LogMiner data dictionaries.

- A capture process scans the redo log for changes using LogMiner.

- The rules engine evaluates changes based on the rules in one or more of the capture process rule sets.

- The capture process enqueues changes that satisfy the rules in its rule sets into a local ANYDATA queue.

- If the captured changes are shared with one or more outbound servers on other databases, then one or more propagations propagate these changes from the source database to the other databases.

Advantages of Local Capture

The following are the advantages of using local capture:

- Configuration and administration of the capture process is simpler than when downstream capture is used. When you use local capture, you do not need to configure redo data copying to a downstream database, and you administer the capture process locally at the database where the captured changes originated.

- A local capture process can scan changes in the online redo log before the database writes these changes to an archived redo log file. When you use an archived-log downstream capture process, archived redo log files are copied to the downstream database after the source database has finished writing changes to them, and some time is required to copy the redo log files to the downstream database. However, a real-time downstream capture process can capture changes in the online redo log sent from the source database.

- The amount of data being sent over the network is reduced, because the redo data is not copied to the downstream database. Even if captured LCRs are propagated to other databases, the captured LCRs can be a subset of the total changes made to the database, and only the LCRs that satisfy the rules in the rule sets for a propagation are propagated.

- Security might be improved because only the source (local) database can access the redo data. For example, if the capture process captures changes in the hr schema only, then, when you use local capture, only the source database can access the redo data to enqueue changes to the hr schema into the capture process queue. However, when you use downstream capture, the redo data is copied to the downstream database, and the redo data contains all of the changes made to the database, not just the changes made to a specific object or schema.

Downstream Capture

Downstream capture means that a capture process runs on a database other than the source database. The following types of downstream capture configurations are possible: real-time downstream capture and archived-log downstream capture. The downstream_real_time_mine capture process parameter controls whether a downstream capture process performs real-time downstream capture or archived-log downstream capture. A real-time downstream capture process and one or more archived-log downstream capture processes can coexist at a downstream database. With downstream capture, the redo log files of the source database must be available at the downstream database.

Note:

- References to "downstream capture processes" in this document apply to both real-time downstream capture processes and archived-log downstream capture processes. This document distinguishes between the two types of downstream capture processes when necessary.

- A downstream capture process only can capture changes from a single source database. However, multiple downstream capture processes at a single downstream database can capture changes from a single source database or multiple source databases.

- To configure XStream Out downstream capture, the source database must be an Oracle Database 10g Release 2 (10.2) or later and the capture database must be an Oracle Database 11g Release 2 (11.2.0.3) or later

Real-Time Downstream Capture

A real-time downstream capture configuration works in the following way:

- Redo transport services sends redo data to the downstream database either synchronously or asynchronously. At the same time, the log writer process (LGWR) records redo data in the online redo log at the source database.

- A remote file server process (RFS) at the downstream database receives the redo data over the network and stores the redo data in the standby redo log.

- A log switch at the source database causes a log switch at the downstream database, and the ARCHn process at the downstream database archives the current standby redo log file.

- The real-time downstream capture process captures changes from the standby redo log whenever possible and from the archived standby redo log files whenever necessary. A capture process can capture changes in the archived standby redo log files if it falls behind. When it catches up, it resumes capturing changes from the standby redo log.

Figure 3-2 Real-Time Downstream Capture

The advantage of real-time downstream capture over archived-log downstream capture is that real-time downstream capture reduces the amount of time required to capture changes made at the source database. The time is reduced because the real-time downstream capture process does not need to wait for the redo log file to be archived before it can capture data from it.

Note:
You can configure more than one real-time downstream capture process that captures changes from the same source database, but you cannot configure real-time downstream capture for multiple source databases at one downstream database.

Archived-Log Downstream Capture

An archived-log downstream capture configuration means that archived redo log files from the source database are copied to the downstream database, and the capture process captures changes in these archived redo log files. You can copy the archived redo log files to the downstream database using redo transport services, the DBMS_FILE_TRANSFER package, file transfer protocol (FTP), or some other mechanism.

Figure 3-3 Archived-Log Downstream Capture

The advantage of archived-log downstream capture over real-time downstream capture is that archived-log downstream capture allows downstream capture processes from multiple source databases at a downstream database. You can copy redo log files from multiple source databases to a single downstream database and configure multiple archived-log downstream capture processes to capture changes in these redo log files.

See Also:
Oracle Data Guard Concepts and Administration for more information about redo transport services

The Downstream Database Performs Most Change Capture Actions

If you configure either real-time or archived-log downstream capture, then the following actions are performed at the downstream database:

- The first time a downstream capture process is started at the downstream database, Oracle Database uses data dictionary information in the redo data from the source database to create a LogMiner data dictionary at the downstream database. The DBMS_CAPTURE_ADM.BUILD procedure is run at the source database to extract the source data dictionary information to the redo log at the source database. Next, the redo data is copied to the downstream database from the source database. Additional downstream capture processes for the same source database can use this existing LogMiner data dictionary, or they can create new LogMiner data dictionaries. Also, a real-time downstream capture process can share a LogMiner data dictionary with one or more archived-log downstream capture processes.

- A capture process scans the redo data from the source database for changes using LogMiner.

- The rules engine evaluates changes based on the rules in one or more of the capture process rule sets.

- The capture process enqueues changes that satisfy the rules in its rule sets into a local ANYDATA queue. The capture process formats the changes as LCRs.

In a downstream capture configuration, the following actions are performed at the source database:

- The DBMS_CAPTURE_ADM.BUILD procedure is run at the source database to extract the data dictionary to the redo log.

- Supplemental logging at the source database places additional information that might be needed for apply in the redo log. See "If Required, Configure Supplemental Logging".

In addition, the redo data must be copied from the computer system running the source database to the computer system running the downstream database. In a real-time downstream capture configuration, redo transport services sends redo data to the downstream database. Typically, in an archived-log downstream capture configuration, redo transport services copies the archived redo log files to the downstream database.

Advantages of Downstream Capture

The following are the advantages of using downstream capture:

- Capturing changes uses fewer resources at the source database because the downstream database performs most of the required work.

- If you plan to capture changes originating at multiple source databases, then capture process administration can be simplified by running multiple archived-log downstream capture processes with different source databases at one downstream database. That is, one downstream database can act as the central location for change capture from multiple sources. In such a configuration, one real-time downstream capture process can run at the downstream database in addition to the archived-log downstream capture processes.

- Copying redo data to one or more downstream databases provides improved protection against data loss. For example, redo log files at the downstream database can be used for recovery of the source database in some situations.

- The ability to configure at one or more downstream databases multiple capture processes that capture changes from a single source database provides more flexibility and can improve scalability.

Optional Database Link From the Downstream Database to the Source Database

When you create or alter a downstream capture process, you optionally can specify the use of a database link from the downstream database to the source database. This database link must have the same name as the global name of the source database. Such a database link simplifies the creation and administration of a downstream capture process. You specify that a downstream capture process uses a database link by setting the use_database_link parameter to TRUE when you run the CREATE_CAPTURE or ALTER_CAPTURE procedure on the downstream capture process. The name of the database link must match the global name of the source database.

When a downstream capture process uses a database link to the source database, the capture process connects to the source database to perform the following administrative actions automatically:

- In certain situations, runs the DBMS_CAPTURE_ADM.BUILD procedure at the source database to extract the data dictionary at the source database to the redo log when a capture process is created.

- Obtains the first SCN for the downstream capture process if the first system change number (SCN) is not specified during capture process creation. The first SCN is needed to create a capture process.

If a downstream capture process does not use a database link, then you must perform these actions manually.

Note:
During the creation of a downstream capture process, if the first_scn parameter is set to NULL in the CREATE_CAPTURE procedure, then the use_database_link parameter must be set to TRUE. Otherwise, an error is raised.

See Also:
Oracle Streams Replication Administrator's Guide for information about when the DBMS_CAPTURE_ADM.BUILD procedure is run automatically during capture process creation if the downstream capture process uses a database link

Operational Requirements for Downstream Capture with XStream Out

The following are operational requirements for using downstream capture:

- The source database must be running at least Oracle Database 10g Release 2 (10.2).

- The XStream Out downstream capture database must be running Oracle Database 11g Release 2 (11.2.0.3) or later and the source database must be running Oracle Database 10g Release 2 (10.2) or later.

- The operating system on the source and downstream capture sites must be the same, but the operating system release does not need to be the same. In addition, the downstream sites can use a different directory structure than the source site.

- The hardware architecture on the source and downstream capture sites must be the same. For example, a downstream capture configuration with a source database on a 64-bit Sun system must have a downstream database that is configured on a 64-bit Sun system. Other hardware elements, such as the number of CPUs, memory size, and storage configuration, can be different between the source and downstream sites.

Capture Processes and RESTRICTED SESSION

When you enable restricted session during system startup by issuing a STARTUP RESTRICT statement, capture processes do not start, even if they were running when the database shut down. When restricted session is disabled with an ALTER SYSTEM statement, each capture process that was running when the database shut down is started.

When restricted session is enabled in a running database by the SQL statement ALTER SYSTEM ENABLE RESTRICTED SESSION clause, it does not affect any running capture processes. These capture processes continue to run and capture changes. If a stopped capture process is started in a restricted session, then the capture process does not actually start until the restricted session is disabled.

Capture Process Subcomponents

A capture process is an optional Oracle background process whose process name is CPnn, where nn can include letters and numbers. A capture process captures changes from the redo log by using the infrastructure of LogMiner. XStream configures LogMiner automatically. You can create, alter, start, stop, and drop a capture process, and you can define capture process rules that control which changes a capture process captures.

The parallelism capture process parameter controls capture process parallelism. When capture process parallelism is 0 (zero), the default for XStream Out, the capture process does not use subcomponents to perform its work. Instead, the CPnn process completes all of the tasks required to capture database changes.

When capture process parallelism is greater than 0, the capture process uses the underlying LogMiner process name is MSnn, where nn can include letters and numbers. When capture process parallelism is 0 (zero), the capture process does not use this process.

When capture process parallelism is greater than 0, the capture process consists of the following subcomponents:

- One reader server that reads the redo log and divides the redo log into regions.

- One or more preparer servers that scan the regions defined by the reader server in parallel and perform prefiltering of changes found in the redo log. Prefiltering involves sending partial information about changes, such as schema and object name for a change, to the rules engine for evaluation, and receiving the results of the evaluation. You can control the number of preparer servers using the parallelism capture process parameter.

- One builder server that merges redo records from the preparer servers. These redo records either evaluated to TRUE during partial evaluation or partial evaluation was inconclusive for them. The builder server preserves the system change number (SCN) order of these redo records and passes the merged redo records to the capture process.

- The capture process (CPnn) performs the following actions for each change when it receives merged redo records from the builder server:

- Formats the change into an LCR

- If the partial evaluation performed by a preparer server was inconclusive for the change in the LCR, then sends the LCR to the rules engine for full evaluation

- Receives the results of the full evaluation of the LCR if it was performed

- Discards the LCR if it satisfies the rules in the negative rule set for the capture process or if it does not satisfy the rules in the positive rule set

- Enqueues the LCR into the queue associated with the capture process if the LCR satisfies the rules in the positive rule set for the capture process

Each reader server, preparer server, and builder server is a process.

Capture Process States

The state of a capture process describes what the capture process is doing currently. You can view the state of a capture process by querying the STATE column in the V$XSTREAM_CAPTURE dynamic performance view.

See Also:
Oracle Database Reference

Capture Process Parameters

After creation, a capture process is disabled so that you can set the capture process parameters for your environment before starting it for the first time. Capture process parameters control the way a capture process operates. For example, the parallelism capture process parameter controls the number of preparer servers used by a capture process, and the time_limit capture process parameter specifies the amount of time a capture process runs before it is shut down automatically. You set capture process parameters using the DBMS_CAPTURE_ADM.SET_PARAMETER procedure.

See Also:
Oracle Database PL/SQL Packages and Types Reference

Capture Process Checkpoints and XStream Out

A checkpoint is information about the current state of a capture process that is stored persistently in the data dictionary of the database running the capture process. A capture process tries to record a checkpoint at regular intervals called checkpoint intervals.

This section contains the following topics:

- Required Checkpoint SCN

- Maximum Checkpoint SCN

- Checkpoint Retention Time

Required Checkpoint SCN

The system change number (SCN) that corresponds to the lowest checkpoint for which a capture process requires redo data is the required checkpoint SCN. The redo log file that contains the required checkpoint SCN, and all subsequent redo log files, must be available to the capture process. If a capture process is stopped and restarted, then it starts scanning the redo log from the SCN that corresponds to its required checkpoint SCN. The required checkpoint SCN is important for recovery if a database stops unexpectedly. Also, if the first SCN is reset for a capture process, then it must be set to a value that is less than or equal to the required checkpoint SCN for the captured process. You can determine the required checkpoint SCN for a capture process by querying the REQUIRED_CHECKPOINT_SCN column in the ALL_CAPTURE data dictionary view.

Maximum Checkpoint SCN

The SCN that corresponds to the last physical checkpoint recorded by a capture process is the maximum checkpoint SCN. The maximum checkpoint SCN can be lower than or higher than the required checkpoint SCN for a capture process. The maximum checkpoint SCN can also be 0 (zero) if the capture process is new and has not yet recorded a physical checkpoint.

Checkpoint Retention Time

The checkpoint retention time is the amount of time, in number of days, that a capture process retains checkpoints before purging them automatically. A capture process periodically computes the age of a checkpoint by subtracting the NEXT_TIME of the archived redo log file that corresponds to the checkpoint from FIRST_TIME of the archived redo log file containing the required checkpoint SCN for the capture process. If the resulting value is greater than the checkpoint retention time, then the capture process automatically purges the checkpoint by advancing its first SCN value. Otherwise, the checkpoint is retained.

You can use the ALTER_CAPTURE procedure in the DBMS_CAPTURE_ADM package to set the checkpoint retention time for a capture process. The DBA_REGISTERED_ARCHIVED_LOG view displays the FIRST_TIME and NEXT_TIME for archived redo log files, and the REQUIRED_CHECKPOINT_SCN column in the ALL_CAPTURE view displays the required checkpoint SCN for a capture process.

See Also:
Oracle Database PL/SQL Packages and Types Reference

SCN Values Related to a Capture Process

This section describes system change number (SCN) values that are important for a capture process. You can query the ALL_CAPTURE data dictionary view to display these values for one or more capture processes.

Captured SCN and Applied SCN

The captured SCN is the SCN that corresponds to the most recent change scanned in the redo log by a capture process. The applied SCN for a capture process is the SCN of the most recent LCR processed by the relevant outbound server. All LCRs lower than this SCN have been processed by all outbound servers that process changes captured by the capture process. The applied SCN for a capture process is equivalent to the low-watermark SCN for an outbound server that processes changes captured by the capture process.

First SCN and Start SCN

The following sections describe the first SCN and start SCN for a capture process:

- First SCN

- Start SCN

- Start SCN Must Be Greater Than or Equal to First SCN

First SCN

The first SCN is the lowest SCN in the redo log from which a capture process can capture changes. If you specify a first SCN during capture process creation, then the database must be able to access redo data from the SCN specified and higher.

The DBMS_CAPTURE_ADM.BUILD procedure extracts the source database data dictionary to the redo log. When you create a capture process, you can specify a first SCN that corresponds to this data dictionary build in the redo log. Specifically, the first SCN for the capture process being created can be set to any value returned by the following query:

COLUMN FIRST_CHANGE# HEADING 'First SCN' FORMAT 999999999
COLUMN NAME HEADING 'Log File Name' FORMAT A50

SELECT DISTINCT FIRST_CHANGE#, NAME FROM V$ARCHIVED_LOG
WHERE DICTIONARY_BEGIN = 'YES';

The value returned for the NAME column is the name of the redo log file that contains the SCN corresponding to the first SCN. This redo log file, and all subsequent redo log files, must be available to the capture process. If this query returns multiple distinct values for FIRST_CHANGE#, then the DBMS_CAPTURE_ADM.BUILD procedure has been run more than once on the source database. In this case, choose the first SCN value that is most appropriate for the capture process you are creating.

In some cases, the DBMS_CAPTURE_ADM.BUILD procedure is run automatically when a capture process is created. When this happens, the first SCN for the capture process corresponds to this data dictionary build.

Start SCN

The start SCN is the SCN from which a capture process begins to capture changes. You can specify a start SCN that is different than the first SCN during capture process creation, or you can alter a capture process to set its start SCN. The start SCN does not need to be modified for normal operation of a capture process. Typically, you reset the start SCN for a capture process if point-in-time recovery must be performed on one of the destination databases that receive changes from the capture process. In these cases, the capture process can capture the changes made at the source database after the point-in-time of the recovery.

Note:
An existing capture process must be stopped before setting its start SCN.

Start SCN Must Be Greater Than or Equal to First SCN

If you specify a start SCN when you create or alter a capture process, then the start SCN specified must be greater than or equal to the first SCN for the capture process. A capture process always scans any unscanned redo log records that have higher SCN values than the first SCN, even if the redo log records have lower SCN values than the start SCN. So, if you specify a start SCN that is greater than the first SCN, then the capture process might scan redo log records for which it cannot capture changes, because these redo log records have a lower SCN than the start SCN.

Scanning redo log records before the start SCN should be avoided if possible because it can take some time. Therefore, Oracle recommends that the difference between the first SCN and start SCN be as small as possible during capture process creation to keep the initial capture process startup time to a minimum.

Caution:
When a capture process is started or restarted, it might need to scan redo log files with a FIRST_CHANGE# value that is lower than start SCN. Removing required redo log files before they are scanned by a capture process causes the capture process to abort. You can query the ALL_CAPTURE data dictionary view to determine the first SCN, start SCN, and required checkpoint SCN. A capture process needs the redo log file that includes the required checkpoint SCN, and all subsequent redo log files.

Outbound Servers

With XStream Out, an Oracle Streams apply process functions as an outbound server. This section describes outbound servers.

This section contains the following topics:

- Overview of Outbound Servers

- Data Types Supported by Outbound Servers

- Apply User for an Outbound Server

- Privileges Required by the Connect User for an Outbound Server

- Outbound Servers and RESTRICTED SESSION

- Outbound Server Components

- Considerations for Outbound Servers

- Outbound Servers and Apply Parameters

Overview of Outbound Servers

An outbound server is an optional Oracle background process that sends database changes to a client application. Specifically, a client application can attach to an outbound server and extract database changes from LCRs. A client application attaches to the outbound server using OCI or Java interfaces.

A client application can create multiple sessions. Each session can attach to only one outbound server, and each outbound server can serve only one session at a time. However, different client application sessions can connect to different outbound servers or inbound servers.

Change capture can be performed on the same database as the outbound server or on a different database. When change capture is performed on a different database from the one that contains the outbound server, a propagation sends the changes from the change capture database to the outbound server database. Downstream capture is also a supported mode to reduce the load on the source database.

When both the outbound server and its capture process are enabled, data changes, encapsulated in row LCRs and DDL LCRs, are sent to the outbound server. The outbound server can publish LCRs in various formats, such as OCI and Java. The client application can process LCRs that are passed to it from the outbound server or wait for LCRs from the outbound server by using a loop.

An outbound server sends LOB, LONG, LONG RAW, and XMLType data to the client application in chunks. Several chunks comprise a single column value of LOB, LONG, LONG RAW, or XMLType data type.

Figure 3-4 shows an outbound server configuration.

Figure 3-4 XStream Out Outbound Server

The client application can detach from the outbound server whenever necessary. When the client application re-attaches, the outbound server automatically determines where in the stream of LCRs the client application was when it detached. The outbound server starts sending LCRs from this point forward.

See Also:
"Capture Processes" for detailed information about capture processes

Data Types Supported by Outbound Servers

Outbound servers support all of the data types that are supported by capture processes. Outbound servers can send LCRs that include changes to columns of these data types to XStream client applications.

See Also:
"Data Types Captured by a Capture Process"

Apply User for an Outbound Server

The apply user for an outbound server is the user who receives LCRs from the outbound server's capture process. The apply user for an outbound server must match the capture user for the outbound server's capture process.

See Also:
"Privileges Required by the Capture User for a Capture Process"

Outbound Servers and RESTRICTED SESSION

When restricted session is enabled during system startup by issuing a STARTUP RESTRICT statement, outbound servers do not start, even if they were running when the database shut down. When the restricted session is disabled, each outbound server that was not stopped is started.

When restricted session is enabled in a running database by the SQL statement ALTER SYSTEM ENABLE RESTRICTED SESSION, it does not affect any running outbound servers. These outbound servers continue to run and send LCRs to an XStream client application. If a stopped outbound server is started in a restricted session, then the outbound server does not actually start until the restricted session is disabled.

Outbound Server Components

An outbound server consists of the following subcomponents:

- A reader server that receives LCRs from the outbound server's capture process. The reader server is a process that computes dependencies between LCRs and assembles LCRs into transactions. The reader server then returns the assembled transactions to the coordinator process.
You can view the state of the reader server for an outbound server by querying the V$XSTREAM_APPLY_READER dynamic performance view. See Oracle Database Reference.

- A coordinator process that gets transactions from the reader server and passes them to apply servers. The coordinator process name is APnn, where nn can include letters and numbers. The coordinator process is an Oracle background process.
You can view the state of a coordinator process by querying the V$XSTREAM_APPLY_COORDINATOR dynamic performance view. See Oracle Database Reference.

- An apply server that sends LCRs to an XStream client application. The apply server is a process. If the apply server encounters an error, then it then it records information about the error in the ALL_APPLY view.
You can view the state of the apply server for an outbound server by querying the V$XSTREAM_APPLY_SERVER dynamic performance view. See Oracle Database Reference.

The reader server and the apply server process names are ASnn, where nn can include letters and numbers.

Considerations for Outbound Servers

The following are considerations for XStream outbound servers:

- LCRs processed by an outbound server must be LCRs that were captured by a capture process. An outbound server does not support LCRs that were constructed by applications.

- A single outbound server can process captured LCRs from only one source database. The source database is the database where the changes encapsulated in the LCRs were generated in the redo log.

- The source database for the changes captured by a capture process must be at 10.2.0 or higher compatibility level for these changes to be processed by an outbound server.

- The capture process for an outbound server must be running on an Oracle Database 11g Release 2 (11.2) or later database.

- A single capture process cannot capture changes for both an outbound server and an apply process. However, a single capture process can capture changes for multiple outbound servers.

- Automatic split and merge of a stream is possible when the capture process and the outbound server for the stream run on different databases. However, when the capture process and outbound server for a stream run on the same database, automatic split and merge of the stream is not possible. See Oracle Streams Replication Administrator's Guide for information about automatic split and merge.

- An outbound server's LCRs can spill from memory to hard disk if they have been in the buffered queue for a period of time without being processed, if there are a large number of LCRs in a transaction, or if there is not enough space in memory to hold all of the LCRs. An outbound server performs best when a minimum of LCRs spill from memory. You can control an outbound server's behavior regarding spilled LCRs using the txn_age_spill_threshold and txn_lcr_spill_threshold apply parameters. See Oracle Database PL/SQL Packages and Types Reference for information about these apply parameters.

- Instantiation SCNs are not required for database objects processed by an outbound server. If an instantiation SCN is set for a database object, then the outbound server only sends the LCRs for the database object with SCN values that are greater than the instantiation SCN value. If a database object does not have an instantiation SCN set, then the outbound server skips the instantiation SCN check and sends all LCRs for that database object. In both cases, the outbound server only sends LCRs that satisfy its rule sets.
See Oracle Streams Replication Administrator's Guide.

Outbound Servers and Apply Parameters

Apply parameters control the behavior of outbound servers. You can use the following apply parameters with outbound servers:

- apply_sequence_nextval

- disable_on_limit

- grouptransops

- ignore_transaction

- max_sga_size

- maximum_scn

- startup_seconds

- time_limit

- trace_level

- transaction_limit

- txn_age_spill_threshold

- txn_lcr_spill_threshold

- write_alert_log

See Also:
Oracle Database PL/SQL Packages and Types Reference

Position of LCRs and XStream Out

An XStream Out outbound server streams LCRs that were captured by a capture process to a client application. This section describes concepts related to the LCR positions for an outbound server.

This section contains these topics:

- Additional LCR Attributes Related to Position in XStream Out

- The Processed Low Position and Restartability for XStream Out

- Streaming Network Transmission

See Also:
"Position Order in an LCR Stream"

Additional LCR Attributes Related to Position in XStream Out

LCRs that were captured by a capture process contain the following additional attributes related to LCR position:

- The scn_from_position attribute contains the SCN of the LCR.

- The commit_scn_from_position attribute contains the commit SCN of the transaction to which the LCR belongs.

Note:
The scn_from_position and commit_scn_from_position attributes are not present in explicitly captured row LCRs.

See Also:
Oracle Database PL/SQL Packages and Types Reference

The Processed Low Position and Restartability for XStream Out

If the outbound server or the client application stops abnormally, then the connection between the two is broken automatically. In this case, the client application must roll back all incomplete transactions.

The processed low position is a position below which all transactions have been processed by the client application. The client application must maintain its processed low position to recover properly after either it or the outbound server (or both) are restarted. The processed low position indicates that the client application has processed all LCRs that are less than or equal to this value. The client application can update the processed low position for each transaction that it consumes.

When the client application attaches to the outbound server, the following conditions related to the processed low position are possible:

- The client application can pass a processed low position to the outbound server that is equal to or greater than the outbound server's processed low position. In this case, the outbound server resumes streaming LCRs from the first LCR that has a position greater than the client application's processed low position.

- The client application can pass a processed low position to the outbound server that is less than the outbound server's processed low position. In this case, the outbound server raises an error.

- The client application can pass NULL to the outbound server. In this case, the outbound server determines the processed low position automatically and starts streaming LCRs from the LCR that has a position greater than this processed low position. When this happens, the client application must suppress or discard each LCR with a position less than or equal to the client application's processed low position.

See Also:
"Displaying the Processed Low Position for an Outbound Server"

Streaming Network Transmission

To minimize network latency, the outbound server streams LCRs to the client application with time-based acknowledgments. For example, the outbound server might send an acknowledgment every 30 seconds. This streaming protocol fully utilizes the available network bandwidth, and the performance is unaffected by the presence of a wide area network (WAN) separating the sender and the receiver. The outbound server extends the underlying Oracle Streams infrastructure, and the outbound server maintains the streaming performance rate.

Using OCI, you can control the time period of the interval by setting the OCI_ATTR_XSTREAM_ACK_INTERVAL attribute through the OCI client application. The default is 30 seconds.

Using Java, you can control the time period of the interval by setting the batchInterval parameter in the attach method in the XStreamOut class. The client application can specify this interval when it invokes the attach method.

If the interval is large, then the outbound server can stream out more LCRs for each acknowledgment interval. However, a longer interval delays how often the client application can send the processed low position to the outbound server. Therefore, a longer interval might mean that the processed low position maintained by the outbound server is not current. In this case, when the outbound server restarts, it must start processing LCRs at an earlier position than the one that corresponds to the processed low position maintained by the client application. Therefore, more LCRs might be retransmitted, and the client application must discard the ones that have been applied.

XStream Out and Distributed Transactions

You can perform distributed transactions using either of the following methods:

- Modify tables in multiple databases in a coordinated manner using database links.

- Use the XA interface, as exposed by the DBMS_XA supplied PL/SQL package or by the OCI or JDBC libraries. The XA interface implements X/Open Distributed Transaction Processing (DTP) architecture.

In an XStream Out configuration, changes made to the source database during a distributed transaction using either of the preceding methods are streamed to an XStream outbound server. The outbound server sends the changes in a transaction to the XStream client application after the transaction has committed.

However, the distributed transaction state is not replicated or sent. The client application does not inherit the in-doubt or prepared state of such a transaction. Also, XStream does not replicate or send the changes using the same global transaction identifier used at the source database for XA transactions.

XA transactions can be performed in two ways:

- Tightly coupled, where different XA branches share locks

- Loosely coupled, where different XA branches do not share locks

XStream supports replication of changes made by loosely coupled XA branches regardless of the COMPATIBLE initialization parameter value. XStream supports replication of changes made by tightly coupled branches on an Oracle RAC source database only if the COMPATIBLE initialization parameter is set to 11.2.0.0 or higher.

See Also:

- Oracle Database Administrator's Guide for more information about distributed transactions

- Oracle Database Development Guide for more information about Oracle XA

XStream Out and Security

This section contains the following topics about XStream Out and security:

- The XStream Out Client Application and Security

- XStream Out Component-Level Security

- Privileges Required by the Capture User for a Capture Process

- Privileges Required by the Connect User for an Outbound Server

See Also:

- "XStream Security Models"

- Oracle Database PL/SQL Packages and Types Reference

The XStream Out Client Application and Security

XStream Out allows an application to receive LCRs. After an XStream Out application receives LCRs, the application might save the contents of LCRs to a file or generate the SQL statements to execute the LCRs on a non-Oracle database.

Java and OCI client applications must connect to an Oracle database before attaching to an XStream outbound server created on that database. The connected user must be the same as the connect_user configured for the outbound server. Otherwise, an error is raised. XStream does not assume that the connected user to the outbound server is trusted.

The XStream Java layer API relies on Oracle JDBC security because XStream accepts the Oracle JDBC connection instance created by client application in the XStream attach method in the XStreamOut class. The connected user is validated as an XStream user.

See Also:

- Oracle Call Interface Programmer's Guide for information about the OCI interface for XStream

- Oracle Database XStream Java API Reference for information about the Java interface for XStream

XStream Out Component-Level Security

All the components of the XStream Out configuration run as the same XStream administrator. This user can be either a trusted user with a high level of privileges, or it can be an untrusted user that has only the privileges necessary for performing certain tasks.

The security model of the XStream administrator also determines the data dictionary views that this user can query to monitor the XStream configuration. The trusted administrator can monitor XStream with DBA_ views. The untrusted administrator can monitor XStream with ALL_ views.

You create an XStream administrator using the GRANT_ADMIN_PRIVILEGE procedure in the DBMS_XSTREAM_AUTH package. When you run this procedure to create an XStream administrator for XStream Out, the privilege_type parameter determines the type of privileges granted to the user:

- Specify CAPTURE for the privilege_type parameter if the XStream administrator manages only an XStream Out configuration on the database.

- Specify * for the privilege_type parameter if the XStream administrator manages both an XStream Out and an XStream In configuration on the database.

The GRANT_ADMIN_PRIVILEGE procedure grants privileges for Oracle-supplied views and packages that are required to run components in an XStream Out or XStream In configuration. This procedure does not grant privileges on database objects owned by users. If such privileges are required, then they must be granted separately.

See Also:
"Configure an XStream Administrator on All Databases" for detailed information about configuring an XStream administrator

Privileges Required by the Capture User for a Capture Process

Changes are captured in the security domain of the capture user for a capture process. The capture user captures all changes that satisfy the capture process rule sets. The capture user must have the necessary privileges to perform these actions.

The capture user must have the following privileges:

- EXECUTE privilege on the rule sets used by the capture process

- EXECUTE privilege on all custom rule-based transformation functions specified for rules in the positive rule set

- Privileges to enqueue LCRs into the capture process queue

A capture process can be associated with only one user, but one user can be associated with many capture processes.

Grant privileges to the capture user with the DBMS_XSTREAM_AUTH package by specifying CAPTURE for the privilege_type parameter in the GRANT_ADMIN_PRIVILEGE procedure.

See Also:

- "Configure an XStream Administrator on All Databases"

- "Changing the Capture User of an Outbound Server's Capture Process"

- Oracle Database XStream Guide for more information about the GRANT_ADMIN_PRIVILEGE procedure

Privileges Required by the Connect User for an Outbound Server

An outbound server sends LCRs to an XStream client application in the security domain of its connect user. The connect user sends LCRs that satisfy the outbound server's rule sets to the XStream client application. In addition, the connect user runs all custom rule-based transformations specified by the rules in these rule sets.

The connect user must have the following privileges:

- EXECUTE privilege on the rule sets used by the outbound server

- EXECUTE privilege on all custom rule-based transformation functions specified for rules in the positive rule set

A outbound server can be associated with only one user, but one user can be associated with many outbound servers.

See Also:

- "XStream Security Models"

- "Privileges Required by the Connect User for an Outbound Server"

- "Configure an XStream Administrator on All Databases"

- "Changing the Connect User for an Outbound Server"

- Oracle Database PL/SQL Packages and Types Reference DBMS_XSTREAM_ADM package "Security Model" for information about the security requirements for configuring and managing XStream

- Oracle Call Interface Programmer's Guide for information about the OCI interface for XStream

- Oracle Database XStream Java API Reference for information about the Java interface for XStream

XStream Out and Other Oracle Database Components

This section describes how XStream Out works with other Oracle Database components.

This section contains these topics:

- XStream Out and Oracle Real Application Clusters

- XStream Out and Transparent Data Encryption

- XStream Out and Flashback Data Archive

- XStream Out and Recovery Manager

- XStream and Distributed Transactions

- XStream Out and a Multitenant Environment

XStream Out and Oracle Real Application Clusters

The following topics describe how XStream Out works with Oracle Real Application Clusters (Oracle RAC):

- Capture Processes and Oracle Real Application Clusters

- Queues and Oracle Real Application Clusters

- Propagations and Oracle Real Application Clusters

- Outbound Servers and Oracle Real Application Clusters

Capture Processes and Oracle Real Application Clusters

A capture process can capture changes in an Oracle Real Application Clusters (Oracle RAC) environment. If you use one or more capture processes and Oracle RAC in the same environment, then all archived logs that contain changes to be captured by a capture process must be available for all instances in the Oracle RAC environment. In an Oracle RAC environment, a capture process reads changes made by all instances. Multiple outbound server processes that use the same capture process must run in the same Oracle RAC instance as the capture process.

You ensure that the capture process runs in the same Oracle RAC instance as its queue by setting the parameter use_rac_service to Y in the procedure DBMS_CAPTURE_ADM.SET_PARAMETER.

If the value for the capture process parameter use_rac_service is set to Y, then each capture process is started and stopped on the owner instance for its ANYDATA queue, even if the start or stop procedure is run on a different instance. Also, a capture process follows its queue to a different instance if the current owner instance becomes unavailable. The queue itself follows the rules for primary instance and secondary instance ownership.

If the value for the capture process parameter use_rac_service is set to N, then the capture process is started on the instance to which the client application connects. Stopping the capture process must be performed on the same instance where the capture process was started.

If the owner instance for a queue table containing a queue used by a capture process becomes unavailable, then queue ownership is transferred automatically to another instance in the cluster. In addition, if the capture process was enabled when the owner instance became unavailable, then the capture process is restarted automatically on the new owner instance. If the capture process was disabled when the owner instance became unavailable, then the capture process remains disabled on the new owner instance.

LogMiner supports the LOG_ARCHIVE_DEST_n initialization parameter, and capture processes use LogMiner to capture changes from the redo log. If an archived log file is inaccessible from one destination, then a local capture process can read it from another accessible destination. On an Oracle RAC database, this ability also enables you to use cross instance archival (CIA) such that each instance archives its files to all other instances. This solution cannot detect or resolve gaps caused by missing archived log files. Hence, it can be used only to complement an existing solution to have the archived files shared between all instances.

In a downstream capture process environment, the source database can be a single instance database or a multi-instance Oracle RAC database. The downstream database can be a single instance database or a multi-instance Oracle RAC database, regardless of whether the source database is single instance or multi-instance.

See Also:

- "Capture Processes"

- Oracle Database Reference for more information about the ALL_QUEUE_TABLES data dictionary view

- Oracle Real Application Clusters Administration and Deployment Guide for more information about configuring archived logs to be shared between instances

Queues and Oracle Real Application Clusters

You can configure queues in an Oracle Real Application Clusters (Oracle RAC) environment. In an Oracle RAC environment, only the owner instance can have a buffer for a queue, but different instances can have buffers for different queues. A buffered queue is System Global Area (SGA) memory associated with a queue.

You set the capture process parameter use_rac_service to Y to specify ownership of the queue table or the primary and secondary instance for a given queue table.

XStream Out processes and jobs support primary instance and secondary instance specifications for queue tables. If use_rac_service is set to Y, you can use the specifications for queue tables and the secondary instance assumes ownership of a queue table when the primary instance becomes unavailable. The queue ownership is transferred back to the primary instance when it becomes available again.

If the owner instance for a queue table containing a destination queue for a propagation becomes unavailable, then queue ownership is transferred automatically to another instance in the cluster. If both the primary and secondary instance for a queue table containing a destination queue become unavailable, then queue ownership is transferred automatically to another instance in the cluster. In this case, if the primary or secondary instance becomes available again, then ownership is transferred back to one of them accordingly.

You can set primary and secondary instance specifications using the ALTER_QUEUE_TABLE procedure in the DBMS_AQADM package. The ALL_QUEUE_TABLES data dictionary view contains information about the owner instance for a queue table. A queue table can contain multiple queues. In this case, each queue in a queue table has the same owner instance as the queue table.

The NETWORK_NAME column in the ALL_QUEUES data dictionary view contains the network name for a queue service. Do not manage the services for queues in any way. Oracle manages them automatically.

See Also:

- Oracle Database Reference for more information about the ALL_QUEUE_TABLES data dictionary view

- Oracle Database Advanced Queuing User's Guide for more information about queues and Oracle RAC

- Oracle Database PL/SQL Packages and Types Reference for more information about the ALTER_QUEUE_TABLE procedure

Propagations and Oracle Real Application Clusters

The information in this section only applies to XStream configurations that include propagations. In a typical XStream configuration, an outbound server and its capture process are configured on the same database, and propagation is not required. The information in this section does not apply to configurations that do not include propagation. However, it is possible to configure a capture process on one database and an outbound server on another database. In this case, a propagation sends LCRs from the capture process's queue to the outbound server's queue.

A propagation can propagate LCRs from one queue to another in an Oracle Real Application Clusters (Oracle RAC) environment. A propagation job running on an instance propagates logical change records (LCRs) from any queue owned by that instance to destination queues.

Before you can propagate LCRs in an Oracle RAC environment, you must set use_rac_service to Y in the procedure DBMS_CAPTURE_ADM.SET_PARAMETER.

Any propagation to an Oracle RAC database is made over database links. The database links must be configured to connect to the destination instance that owns the queue that will receive the LCRs.

A queue-to-queue propagation to a buffered destination queue uses a service to provide transparent failover in an Oracle RAC environment. That is, a propagation job for a queue-to-queue propagation automatically connects to the instance that owns the destination queue. The service used by a queue-to-queue propagation always runs on the owner instance of the destination queue. This service is created only for buffered queues in an Oracle RAC database. If you plan to use buffered messaging with an Oracle RAC database, then LCRs can be enqueued into a buffered queue on any instance. If LCRs are enqueued on an instance that does not own the queue, then the LCRs are sent to the correct instance, but it is more efficient to enqueue LCRs on the instance that owns the queue. You can use the service to connect to the owner instance of the queue before enqueuing LCRs into a buffered queue.

Because the queue service always runs on the owner instance of the queue, transparent failover can occur when Oracle RAC instances fail. When multiple queue-to-queue propagations use a single database link, the connect description for each queue-to-queue propagation changes automatically to propagate LCRs to the correct destination queue.

Note:
If a queue contains or will contain captured LCRs in an Oracle RAC environment, then use queue-to-queue propagations to propagate LCRs to an Oracle RAC destination database.

Outbound Servers and Oracle Real Application Clusters

You can configure an outbound server in an Oracle Real Application Clusters (Oracle RAC) environment provided you have set use_rac_service to Y in the procedure DBMS_CAPTURE_ADM.SET_PARAMETER.

Each outbound server is started and stopped on the owner instance for its ANYDATA queue, even if the start or stop procedure is run on a different instance. A coordinator process, its corresponding apply reader server, and its apply server run on a single instance. Multiple XStream Out processes that use the same capture process must run in the same Oracle RAC instance as the capture process.

If the owner instance for a queue table containing a queue used by an outbound server becomes unavailable, then queue ownership is transferred automatically to another instance in the cluster. Also, an outbound server will follow its queue to a different instance if the current owner instance becomes unavailable. The queue itself follows the rules for primary instance and secondary instance ownership. In addition, if the outbound server was enabled when the owner instance became unavailable, then the outbound server is restarted automatically on the new owner instance. If the outbound server was disabled when the owner instance became unavailable, then the outbound server remains disabled on the new owner instance.

See Also:

- "Outbound Servers"

- Oracle Database Reference for more information about the ALL_QUEUE_TABLES data dictionary view

XStream Out and Transparent Data Encryption

The following topics describe how XStream Out works with Transparent Data Encryption:

See Also:
Oracle Database Advanced Security Guide for information about Transparent Data Encryption

Capture Processes and Transparent Data Encryption

A local capture process can capture changes to columns that have been encrypted using Transparent Data Encryption. A downstream capture process can capture changes to columns that have been encrypted only if the downstream database shares an encryption keystore (container for authentication and signing credentials) with the source database. A keystore can be shared through a network file system (NFS), or it can be copied from one computer system to another manually. When a keystore is shared with a downstream database, ensure that the ENCRYPTION_WALLET_LOCATION parameter in the sqlnet.ora file at the downstream database specifies the keystore location.

If you copy a keystore to a downstream database, then ensure that you copy the keystore from the source database to the downstream database whenever the keystore at the source database changes. Do not perform any operations on the keystore at the downstream database, such as changing the encryption key for a replicated table.

Encrypted columns in row logical change records (row LCRs) captured by a local or downstream capture process are decrypted when the row LCRs are staged in a buffered queue.

Note:
A capture process only supports encrypted columns if the redo logs used by the capture process were generated by a database with a compatibility level of 11.0.0 or higher. The compatibility level is controlled by the COMPATIBLE initialization parameter.

See Also:
"Capture Processes"

Propagations and Transparent Data Encryption

The information in this section only applies to XStream configurations that include propagations. In a typical XStream configuration, an outbound server and its capture process are configured on the same database, and propagation is not required. The information in this section does not apply to configurations that do not include propagation. However, it is possible to configure a capture process on one database and an outbound server on another database. In this case, a propagation sends LCRs from the capture process's queue to the outbound server's queue.

A propagation can propagate row logical change records (row LCRs) that contain changes to columns that were encrypted using Transparent Data Encryption. When a propagation propagates row LCRs with encrypted columns, the encrypted columns are decrypted while the row LCRs are transferred over the network. You can use the features of Oracle Advanced Security to encrypt data transfers over the network if necessary.

See Also:
Oracle Database Security Guide for information about configuring network data encryption

Outbound Servers and Transparent Data Encryption

An outbound server can process implicitly captured row logical change records (row LCRs) that contain columns encrypted using Transparent Data Encryption. When row LCRs with encrypted columns are processed by an outbound server, the encrypted columns are decrypted. These row LCRs with decrypted columns are sent to the XStream client application.

When row LCRs with encrypted columns are stored in buffered queues, the columns are decrypted. When row LCRs spill to disk, XStream transparently encrypts any encrypted columns while the row LCRs are stored on disk.

Note:
For XStream Out to encrypt columns transparently, the encryption master key must be stored in the keystore on the local database, and the keystore must be open. The following statements set the master key and open the keystore:

ALTER SYSTEM SET ENCRYPTION KEY IDENTIFIED BY key-password;

ALTER SYSTEM SET ENCRYPTION WALLET OPEN IDENTIFIED BY key-password;

Because the same keystore needs to be available and open in any instance where columns are encrypted, make sure you copy the keystore to the downstream capture database. In the case of a downstream capture, you must also run the above commands on the downstream instance.

See Also:
"Outbound Servers"

XStream Out and Flashback Data Archive

XStream Out supports tables in a flashback data archive. Capture processes can capture data manipulation language (DML) and data definition language (DDL) changes made to these tables. Outbound servers can process the captured LCRs.

XStream Out also support the following DDL statements:

- CREATE FLASHBACK ARCHIVE

- ALTER FLASHBACK ARCHIVE

- DROP FLASHBACK ARCHIVE

- CREATE TABLE with a FLASHBACK ARCHIVE clause

- ALTER TABLE with a FLASHBACK ARCHIVE clause

Note:
XStream Out does not capture changes made to internal tables used by a flashback data archive.

See Also:

- Oracle Database Development Guide for information about flashback data archive

- "Capture Processes"

- "Outbound Servers"

XStream Out and Recovery Manager

Some RMAN deletion policies and commands delete archived redo log files. If one of these RMAN policies or commands is used on a database that generates redo log files for one or more capture processes, then ensure that the RMAN commands do not delete archived redo log files that are required by a capture process.

The following sections describe the behavior of RMAN deletion policies and commands for local capture processes and downstream capture processes

- RMAN and Local Capture Processes

- RMAN and Downstream Capture Processes

See Also:

- "Capture Processes"

- "The Capture Process Is Missing Required Redo Log Files" for information about determining whether a capture process is missing required archived redo log files and for information correcting this problem

- "Checking the Trace File and Alert Log for Problems"

- Oracle Database Backup and Recovery User's Guide and Oracle Database Backup and Recovery Reference for more information about RMAN

RMAN and Local Capture Processes

When a local capture process is configured, RMAN does not delete archived redo log files that are required by the local capture process unless there is space pressure in the fast recovery area. Specifically, RMAN does not delete archived redo log files that contain changes with system change number (SCN) values that are equal to or greater than the required checkpoint SCN for the local capture process. This is the default RMAN behavior for all RMAN deletion policies and DELETE commands, including DELETE ARCHIVELOG and DELETE OBSOLETE.

When there is not enough space in the fast recovery area to write a new log file, RMAN automatically deletes one or more archived redo log files. Oracle Database writes warnings to the alert log when RMAN automatically deletes an archived redo log file that is required by a local capture process.

When backups of the archived redo log files are taken on the local capture process database, Oracle recommends the following RMAN deletion policy:

CONFIGURE ARCHIVELOG DELETION POLICY TO BACKED UP integer TIMES
TO DEVICE TYPE deviceSpecifier;

This deletion policy requires that a log file be backed up integer times before it is considered for deletion.

When no backups of the archived redo log files are taken on the local capture process database, no specific deletion policy is recommended. By default, RMAN does not delete archived redo log files that are required by a local capture process.

RMAN and Downstream Capture Processes

When a downstream capture process captures database changes made at a source database, ensure that no RMAN deletion policy or command deletes an archived redo log file until after it is transferred from the source database to the downstream capture process database.

The following are considerations for specific RMAN deletion policies and commands that delete archived redo log files:

- The RMAN command CONFIGURE ARCHIVELOG DELETION POLICY sets a deletion policy that determines when archived redo log files in the fast recovery area are eligible for deletion. The deletion policy also applies to all RMAN DELETE commands, including DELETE ARCHIVELOG and DELETE OBSOLETE.
The following settings determine the behavior at the source database:

- A deletion policy set TO SHIPPED TO STANDBY does not delete a log file until after it is transferred to a downstream capture process database that requires the file. These log files might or might not have been processed by the downstream capture process. Automatic deletion occurs when there is not enough space in the fast recovery area to write a new log file.

- A deletion policy set TO APPLIED ON STANDBY does not delete a log file until after it is transferred to a downstream capture process database that requires the file and the source database marks the log file as applied. The source database marks a log file as applied when the minimum required checkpoint SCN of all of the downstream capture processes for the source database is greater than the highest SCN in the log file.

- A deletion policy set to BACKED UP integer TIMES TO DEVICE TYPE requires that a log file be backed up integer times before it is considered for deletion. A log file can be deleted even if the log file has not been processed by a downstream capture process that requires it.

- A deletion policy set TO NONE means that a log file can be deleted when there is space pressure on the fast recovery area, even if the log file has not been processed by a downstream capture process that requires it.

- The RMAN command DELETE ARCHIVELOG deletes archived redo log files that meet all of the following conditions:

- The log files satisfy the condition specified in the DELETE ARCHIVELOG command.

- The log files can be deleted according to the CONFIGURE ARCHIVELOG DELETION POLICY. For example, if the policy is set TO SHIPPED TO STANDBY, then this command does not delete a log file until after it is transferred to any downstream capture process database that requires it.

This behavior applies when the database is mounted or open.

If archived redo log files are not deleted because they contain changes required by a downstream capture process, then RMAN displays a warning message about skipping the delete operation for these files.

- The RMAN command DELETE OBSOLETE permanently purges the archived redo log files that meet all of the following conditions:

- The log files are obsolete according to the retention policy.

- The log files can be deleted according to the CONFIGURE ARCHIVELOG DELETION POLICY. For example, if the policy is set TO SHIPPED TO STANDBY, then this command does not delete a log file until after it is transferred to any downstream capture process database that requires it.

This behavior applies when the database is mounted or open.

- The RMAN command BACKUP ARCHIVELOG ALL DELETE INPUT copies the archived redo log files and deletes the original files after completing the backup. This command does not delete the log file until after it is transferred to a downstream capture process database when the following conditions are met:

- The database is mounted or open.

- The log file is required by a downstream capture process.

- The deletion policy is set TO SHIPPED TO STANDBY.

If archived redo log files are not deleted because they contain changes required by a downstream capture process, then RMAN displays a warning message about skipping the delete operation for these files.

Oracle recommends one of the following RMAN deletion policies at the source database for a downstream capture process:

- When backups of the archived redo log files are taken on the source database, set the deletion policy to the following:

CONFIGURE ARCHIVELOG DELETION POLICY TO SHIPPED TO STANDBY
BACKED UP integer TIMES TO DEVICE TYPE deviceSpecifier;

- When no backups of the archived redo log files are taken on the source database, set the deletion policy to the following:

CONFIGURE ARCHIVELOG DELETION POLICY TO SHIPPED TO STANDBY;

Note:
At a downstream capture process database, archived redo log files transferred from a source database are not managed by RMAN.

XStream and Distributed Transactions

You can perform distributed transactions using either of the following methods:

- Modify tables in multiple databases in a coordinated manner using database links.

- Use the XA interface, as exposed by the DBMS_XA supplied PL/SQL package or by the OCI or JDBC libraries. The XA interface implements X/Open Distributed Transaction Processing (DTP) architecture.

A capture process captures changes made to the source database during a distributed transaction using either of these two methods and sends the changes to an outbound server. An outbound server sends the changes in a transaction to a client application after the transaction has committed.

However, the distributed transaction state is not sent. The client application does not inherit the in-doubt or prepared state of such a transaction. Also, the outbound server does not send the changes using the same global transaction identifier used at the source database for XA transactions.

XA transactions can be performed in two ways:

- Tightly coupled, where different XA branches share locks

- Loosely coupled, where different XA branches do not share locks

XStream Out supports changes made by loosely coupled XA branches regardless of the COMPATIBLE initialization parameter value. XStream Out supports replication of changes made by tightly coupled branches on an Oracle RAC source database only if the COMPATIBLE initialization parameter set to 11.2.0.0 or higher.

See Also:

- Oracle Database Administrator's Guide for more information about distributed transactions

- Oracle Database Development Guide for more information about Oracle XA

XStream Out and a Multitenant Environment

A multitenant environment enables an Oracle database to contain a portable set of schemas, objects, and related structures that appears logically to an application as a separate database. This self-contained collection is called a pluggable database (PDB). A multitenant container database (CDB) contains PDBs. This section assumes that you understand multitenant architecture concepts. See Oracle Database Concepts for information.

In a CDB, XStream Out functions much the same as it does in a non-CDB. The main differences are:

- XStream Out must be configured in the root and not in any of the PDBs.

- XStream Out can see changes made to any container within the CDB (root and all the PDBs).

- XStream Out capture rules can limit the LCRs to those that are needed for the client application. The system-generated capture rules select the appropriate LCRs based on the parameters that were passed to the ADD_OUTBOUND and CREATE_OUTBOUND procedures in the DBMS_XSTREAM_ADM package. You can use the ADD_*_RULES procedures in the same package for more fine-grained control over the rules used by the XStream Out components.

- The user who performs XStream Out tasks must be a common user.

See Also:

- "System-Created Rules and a Multitenant Environment"

- "Configuring XStream Out with Local Capture in a CDB"

- Oracle Database Administrator's Guide

Unplug and Plug Operations

When a PDB involved with XStream Out is unplugged from its CDB and plugged into another CDB, any capture process or outbound server is not considered part of the PDB. You must configure the capture process and outbound server again in the new CDB.

If an outbound server is configured in a different database than the capture process, then unplug and plug operations have additional considerations.

For this example, assume the following:

- A CDB A with PDB PDB1.

- A capture process is configured in CDB A, and it sends LCRs from PDB1 to an outbound server in CDB B.

- You unplug PDB1 from CDB A, and plug it into CDB C.

To continue delivering LCRs from PDB1 to the outbound server in CDB B, you must configure a new capture process in CDB C to capture and send LCRs to CDB B.

The rules used by the outbound server in database B must be altered to change references to the root of CDB A to the root of CDB C. In addition, if PDB1 was given a different name in CDB C, then the rules must be altered to reflect the new PDB name.

4 Configuring XStream Out

This chapter describes configuring the Oracle Database components that are used by XStream.

This chapter contains these topics:

- Preparing for XStream Out

- Configuring XStream Out

See Also:

- Chapter 3, "XStream Out Concepts"

- "XStream Use Cases"

- Oracle Call Interface Programmer's Guide

- Oracle Database XStream Java API Reference

Preparing for XStream Out

This section describes the decisions to make and the tasks to complete to prepare for an XStream Out configuration.

- Decide How to Configure XStream Out

- Prerequisites for Configuring XStream Out

Decide How to Configure XStream Out

When you configure XStream Out, you must configure XStream components to capture database changes and send these changes to the outbound server in the form of logical change records (LCRs). These components include a capture process and at least one queue. The capture process can be a local capture process or a downstream capture process. For some configurations, you must also configure a propagation.

Local capture means that a capture process runs on the source database. Downstream capture means that a capture process runs on a database other than the source database. The source database is the database where the changes were generated. The primary reason to use downstream capture is to reduce the load on the source database, thereby improving its performance. The primary reason to use a local capture is because it is easier to configure and maintain.

The database that captures changes made to the source database is called the capture database. One of the following databases can be the capture database:

- Source database (local capture)

- Destination database (downstream capture)

- A third database (downstream capture)

If the database running the outbound server is not the capture database, then a propagation sends changes from the capture database to the database running the outbound server. If the database running the outbound server is the capture database, then this propagation between databases is not needed because the capture process and outbound server use the same queue.

You can configure the components in the following ways:

- Local capture and outbound server in the same database: The database objects, capture process, and outbound server are all in the same database. This configuration is the easiest to configure and maintain because all of the components are contained in one database. See Figure 4-1 for an overview of this configuration.

- Local capture and outbound server in different databases: The database objects and capture process are in one database, and the outbound server is in another database. A propagation sends LCRs from the source database to the outbound server database. This configuration is best when you want easy configuration and maintenance and when you want to optimize the performance of the outbound server database. See Figure 4-2 for an overview of this configuration.

- Downstream capture and outbound server in the same database: The database objects are in one database, and the capture process and outbound server are in another database. This configuration is best when you want to optimize the performance of the database with the database objects and want to offload change capture to another database. With this configuration, most of the components run on the database with the outbound server. See Figure 4-3 for an overview of this configuration.

- Downstream capture and outbound server in different databases: The database objects are in one database, the outbound server is in another database, and the capture process is in a third database. This configuration is best when you want to optimize the performance of both the database with the database objects and the database with the outbound server. With this configuration, the capture process runs on a third database, and a propagation sends LCRs from the capture database to the outbound server database. See Figure 4-4 for an overview of this configuration.

The following figures illustrate these different configurations.

Figure 4-1 Local Capture and Outbound Server in the Same Database

Figure 4-2 Local Capture and Outbound Server in Different Databases

Figure 4-3 Downstream Capture and Outbound Server in the Same Database

Figure 4-4 Downstream Capture and Outbound Server in Different Databases

If you decide to configure a downstream capture process, then you must decide which type of downstream capture process you want to configure. The following types are available:

- A real-time downstream capture process configuration means that redo transport services at the source database sends redo data to the downstream database, and a remote file server process (RFS) at the downstream database receives the redo data over the network and stores the redo data in the standby redo log, where the capture process captures changes in real-time.

- An archived-log downstream capture process configuration means that archived redo log files from the source database are copied to the downstream database, and the capture process captures changes in these archived redo log files. These log files can be transferred automatically using redo transport services, or they can be transferred manually using a method such as FTP.

The advantage of real-time downstream capture over archived-log downstream capture is that real-time downstream capture reduces the amount of time required to capture changes made to the source database. The time is reduced because the real-time downstream capture process does not need to wait for the redo log file to be archived before it can capture changes from it. You can configure multiple real-time downstream capture processes that capture changes from the same source database, but you cannot configure real-time downstream capture for multiple source databases at one downstream database.

The advantage of archived-log downstream capture over real-time downstream capture is that archived-log downstream capture allows downstream capture processes for multiple source databases at a downstream database. You can copy redo log files from multiple source databases to a single downstream database and configure multiple archived-log downstream capture processes to capture changes in these redo log files.

See Also:
"Local Capture and Downstream Capture"

Prerequisites for Configuring XStream Out

Preparing for an XStream Out outbound server is similar to preparing for an Oracle Streams replication environment. The components used in an Oracle Streams replication environment to capture changes and send them to an apply process are the same components used to capture changes and send them to an outbound server. These components include a capture process and one or more queues. If the capture process runs on a different database than the outbound server, then a propagation is also required.

Several of the tasks described in this section are described in more detail in Oracle Streams Replication Administrator's Guide. This section provides an overview of each task and specific information about completing the task for an XStream Out configuration.

Ensure that the following prerequisites are met before configuring XStream Out:

- Configure an XStream Administrator on All Databases

- If Required, Configure Network Connectivity and Database Links

- Ensure That Each Source Database Is in ARCHIVELOG Mode

- Set the Relevant Initialization Parameters

- Configure the Streams pool

- If Required, Configure Supplemental Logging

- If Required, Configure Log File Transfer to a Downstream Database

- If Required, Add Standby Redo Logs for Real-Time Downstream Capture

Configure an XStream Administrator on All Databases

An XStream administrator configures and manages XStream components in an XStream Out environment. This section describes configuring an XStream administrator by granting a user the appropriate privileges. You must configure an XStream administrator in each Oracle database included in the XStream configuration.

Prerequisites

Before configuring an XStream administrator, ensure that the following prerequisites are met:

- Ensure that you can log in to each database in the XStream configuration as an administrative user who can create users, grant privileges, and create tablespaces.

- Decide between the trusted user model and untrusted user model for security. See XStream Security Models for more information.

- Identify a user who will be the XStream administrator. Either create a new user with the appropriate privileges or grant these privileges to an existing user.
Do not use the SYS or SYSTEM user as an XStream administrator, and ensure that the XStream administrator does not use the SYSTEM tablespace as its default tablespace.

- If a new tablespace is required for the XStream administrator, then ensure that there is enough disk space on each computer system in the XStream configuration for the tablespace. The recommended size of the tablespace is 25 MB.

Assumptions

This section makes the following assumptions:

- The username of the XStream administrator is xstrmadmin for a non-CDB. The username of the XStream administrator is c##xstrmadmin for a multitenant container database (CDB).

- The tablespace used by the XStream administrator is xstream_tbs.

To configure an XStream administrator:

1. In SQL*Plus, connect as an administrative user who can create users, grant privileges, and create tablespaces. Remain connected as this administrative user for all subsequent steps.

If you are configuring an XStream administrator for XStream Out in a CDB, then connect to the root and configure the XStream administrator in the root. See "XStream Out and a Multitenant Environment" for more information about XStream Out and CDBs.

See Also:
Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus

2. Either create a tablespace for the XStream administrator or use an existing tablespace.
This tablespace stores any objects created in the XStream administrator's schema.

For example, the following statement creates a new tablespace for the XStream administrator:

CREATE TABLESPACE xstream_tbs DATAFILE '/usr/oracle/dbs/xstream_tbs.dbf'
SIZE 25M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED;

If you are creating an XStream administrator in a CDB, then you must create the tablespace in the root and in all pluggable databases (PDBs). The tablespace is required in all PDBs because the XStream administrator must be a common user and so must have access to the tablespace in any PDB.

3. Create a new user to act as the XStream administrator or identify an existing user.

For example, to create a user named xstrmadmin and specify that this user uses the xstream_tbs tablespace, run the following statement:

CREATE USER xstrmadmin IDENTIFIED BY password
DEFAULT TABLESPACE xstream_tbs
QUOTA UNLIMITED ON xstream_tbs;

If you are creating an XStream administrator in a CDB, then the XStream administrator must be a common user. Therefore, include the CONTAINER=ALL clause in the CREATE USER statement:

CREATE USER c##xstrmadmin IDENTIFIED BY password
DEFAULT TABLESPACE xstream_tbs
QUOTA UNLIMITED ON xstream_tbs
CONTAINER=ALL;

Note:
Enter an appropriate password for the administrative user.

See Also:
Oracle Database Security Guide for guidelines about choosing passwords

4. Grant CREATE SESSION privilege to the XStream administrator.
If you created a new user to act as the XStream administrator, then grant this user CREATE SESSION privilege.

For example, to grant CREATE SESSION privilege to user xstrmadmin, run the following statement:

GRANT CREATE SESSION TO xstrmadmin;

If you are creating an XStream administrator in a CDB, then grant CREATE SESSION privilege and SET CONTAINER privilege to the XStream administrator, and include the CONTAINER=ALL clause in the statement.

For example, to grant these privileges to user c##xstrmadmin in a CDB, run the following statement:

GRANT CREATE SESSION, SET CONTAINER TO c##xstrmadmin CONTAINER=ALL;

5. Run the GRANT_ADMIN_PRIVILEGE procedure in the DBMS_XSTREAM_AUTH package.
A user must have explicit EXECUTE privilege on a package to execute a subprogram in the package inside of a user-created subprogram, and a user must have explicit READ or SELECT privilege on a data dictionary view to query the view inside of a user-created subprogram. These privileges cannot be granted through a role. You can run the GRANT_ADMIN_PRIVILEGE procedure to grant such privileges to the XStream administrator, or you can grant them directly.

Depending on the parameter settings for the GRANT_ADMIN_PRIVILEGE procedure, it can grant the appropriate privileges for a trusted or untrusted XStream administrator, and it can grant privileges in a non-CDB or a CDB. Table 4-1 describes key parameter settings for each case.

Table 4-1 Key Parameter Settings for GRANT_ADMIN_PRIVILEGE

Type of XStream Administrator

grant_select_privileges Parameter Setting

container Parameter Setting

Trusted in a non-CDB

TRUE

CURRENT (default)

Untrusted in a non-CDB

FALSE (default)

CURRENT (default)

Trusted in a CDB

TRUE

ALL

Untrusted in a CDB

FALSE (default)

ALL

Example 4-1 Granting Privileges to a Trusted XStream Administrator in a Non-CDB Without Generating a Script

BEGIN
DBMS_XSTREAM_AUTH.GRANT_ADMIN_PRIVILEGE(
grantee                 => 'xstrmadmin',
privilege_type          => 'CAPTURE',
grant_select_privileges => TRUE);
END;
/

Example 4-2 Granting Privileges to a Trusted XStream Administrator in a Non-CDB and Generating a Script

The directory specified in the directory_name parameter must exist and must be accessible to the current user.

BEGIN
DBMS_XSTREAM_AUTH.GRANT_ADMIN_PRIVILEGE(
grantee                 => 'xstrmadmin',
privilege_type          => 'CAPTURE',
grant_select_privileges => TRUE,
do_grants               => TRUE,
file_name               => 'grant_xstrm_privs.sql',
directory_name          => 'xstrm_dir');
END;
/

Example 4-3 Granting Privileges to an Untrusted XStream Administrator in a Non-CDB Without Generating a Script

BEGIN
DBMS_XSTREAM_AUTH.GRANT_ADMIN_PRIVILEGE(
grantee                 => 'xstrmadmin',
privilege_type          => 'CAPTURE',
grant_select_privileges => FALSE);
END;
/

Example 4-4 Granting Privileges to a Trusted XStream Administrator in a CDB Without Generating a Script

BEGIN
DBMS_XSTREAM_AUTH.GRANT_ADMIN_PRIVILEGE(
grantee                 => 'c##xstrmadmin',
privilege_type          => 'CAPTURE',
grant_select_privileges => TRUE,
container               => 'ALL');
END;
/

Note:
For any scenario, when the XStream administrator must manage both an XStream Out and an XStream In configuration on the database, specify * for the privilege_type parameter.

See Also:
Oracle Database PL/SQL Packages and Types Reference

6. If necessary, grant additional privileges to the XStream administrator.
See "Granting Additional Privileges to the XStream Administrator".

7. Repeat all of the previous steps at each Oracle database in the environment that will use XStream.

Granting Additional Privileges to the XStream Administrator

Grant any of the following additional privileges to the XStream Administrator if necessary:

- If you plan to use Oracle Enterprise Manager Cloud Control to manage databases with XStream components, then the XStream administrator must be a trusted user and must be granted DBA role. You must also configure the XStream administrator to be an Oracle Enterprise Manager administrative user. Doing so grants additional privileges required by Oracle Enterprise Manager Cloud Control, such as the privileges required to run Oracle Enterprise Manager Cloud Control jobs. See the Oracle Enterprise Manager Cloud Control online help for information about creating Oracle Enterprise Manager administrative users.

- Grant the privileges for a remote XStream administrator to perform actions in the local database. Grant these privileges using the GRANT_REMOTE_ADMIN_ACCESS procedure in the DBMS_XSTREAM_AUTH package. Grant this privilege if a remote XStream administrator will use a database link that connects to the local XStream administrator to perform administrative actions. Specifically, grant these privileges if either of the following conditions are true:

- You plan to configure a downstream capture process at a remote downstream database that captures changes originating at the local source database, and the downstream capture process will use a database link to perform administrative actions at the source database.

- You plan to use a remote XStream administrator to set the instantiation system change number (SCN) values for replicated database objects at the local database.

- Grant the XStream administrator EXECUTE privilege on any PL/SQL function owned by another user that is specified in a custom rule-based transformation for a rule used by a capture process, propagation, or outbound server. For a capture process, if a capture user is specified, then the capture user must have these privileges. These privileges must be granted directly. They cannot be granted through a role.

- Grant the XStream administrator privileges to alter database objects where appropriate. For example, if the XStream administrator must create a supplemental log group for a table in another schema, then the XStream administrator must have the necessary privileges to alter the table. These privileges can be granted directly or through a role.

- If the XStream administrator does not own the queue used by a capture process, propagation, or outbound server, and is not specified as the queue user for the queue when the queue is created, then the XStream administrator must be configured as a secure queue user of the queue if you want the XStream administrator to be able to enqueue LCRs into or dequeue LCRs from the queue. The XStream administrator might also need ENQUEUE or DEQUEUE privileges on the queue, or both. See Oracle Streams Concepts and Administration for information about managing queues.

- Grant the XStream administrator EXECUTE privilege on any object types that the XStream administrator might need to access. These privileges can be granted directly or through a role.

- If you are using Oracle Database Vault, then the XStream administrator must be granted the DV_XSTREAM_ADMIN role to perform the following tasks: create a capture process, create an outbound server, and modify the capture user for a capture process. When the XStream administrator is not performing these tasks, you can revoke DV_XSTREAM_ADMIN role from the XStream administrator.
In addition, the user who performs the following actions must be granted the BECOME USER system privilege:

- Creates or alters a capture process

- Creates or alters an outbound server

Granting the BECOME USER system privilege to the user who performs these actions is not required if Oracle Database Vault is not installed. You can revoke the BECOME USER system privilege from the user after the completing one of these actions, if necessary.

See Oracle Database Vault Administrator's Guide.

If Required, Configure Network Connectivity and Database Links

Network connectivity and database links are not required when all of the components run on the same database. These components include the capture process, queue, and outbound server.

You must configure network connectivity and database links if you decided to configure XStream in either of the following ways:

- The capture process and the outbound server will run on different databases.

- Downstream capture will be used.

See "Decide How to Configure XStream Out" for more information about these decisions.

If network connectivity is required, then configure your network and Oracle Net so that the databases can communicate with each other.

The following database links are required:

- When the capture process runs on a different database from the outbound server, create a database link from the capture database to the outbound server database. A propagation uses this database link to send changes from the capture database to the outbound server database.

- When you use downstream capture, create a database link from the capture database to the source database. The source database is the database that generates the redo data that the capture process uses to capture changes. The capture process uses this database link to perform administrative tasks at the source database.

The name of each database link must match the global name of the destination database, and each database link should be created in the XStream administrator's schema.

For example, assume that you want to create a database link in a configuration with the following characteristics:

- The global name of the source database is dbs1.example.com.

- The global name of the destination database is dbs2.example.com.

- The XStream administrator is xstrmadmin at each database.

Given these assumptions, the following statement creates a database link from dbs1.example.com to dbs2.example.com:

CONNECT xstrmadmin@dbs1.example.com
Enter password: password

CREATE DATABASE LINK dbs2.example.com CONNECT TO xstrmadmin
IDENTIFIED BY password USING 'dbs2.example.com';

See Also:

- Oracle Database 2 Day DBA

- Oracle Database Administrator's Guide for more information about database links

Ensure That Each Source Database Is in ARCHIVELOG Mode

Each source database that generates changes that will be captured by a capture process must be in ARCHIVELOG mode. For downstream capture processes, the downstream database also must be in ARCHIVELOG mode if you plan to configure a real-time downstream capture process. The downstream database does not need to be in ARCHIVELOG mode if you plan to run only archived-log downstream capture processes on it.

If you are configuring XStream in an Oracle Real Application Clusters (Oracle RAC) environment, then the archived redo log files of all threads from all instances must be available to any instance running a capture process. This requirement pertains to both local and downstream capture processes.

See Also:
Oracle Database Administrator's Guide for instructions about running a database in ARCHIVELOG mode

Set the Relevant Initialization Parameters

Some initialization parameters are important for the configuration, operation, reliability, and performance of the components in an XStream configuration. Set these parameters appropriately.

The following requirements apply to XStream outbound servers:

- Ensure that the PROCESSES initialization parameter is set to a value large enough to accommodate the outbound server background processes and all of the other Oracle Database background processes.

- Ensure that the SESSIONS initialization parameter is set to a value large enough to accommodate the sessions used by the outbound server background processes and all of the other Oracle Database sessions.

Configure the Streams pool

The Streams pool is a portion of memory in the System Global Area (SGA) that is used by both Oracle Streams and XStream components. The Streams pool stores buffered queue LCRs in memory, and it provides memory for capture processes and outbound servers.

The following are considerations for configuring the Streams pool:

- At least 300 MB of memory is required for the Streams pool.

- After XStream Out is configured, you can use the max_sga_size capture process parameter to control the amount of system global area (SGA) memory allocated specifically to a capture process.
The sum of system global area (SGA) memory allocated for all components on a database must be less than the value set for the STREAMS_POOL_SIZE initialization parameter.

- After XStream Out is configured, you can use the max_sga_size apply parameter to control the amount of SGA memory allocated specifically to an outbound server.

- Ensure that there is enough space in the Streams pool at each database to run XStream components and to store LCRs and run the components properly.

- The Streams pool is initialized the first time an outbound server is started.

- The best practice is to set the STREAMS_POOL_SIZE initialization parameter explicitly to the desired Streams pool size.

The Automatic Shared Memory Management feature automatically manages the size of the Streams pool when the following conditions are met:

- The MEMORY_TARGET and MEMORY_MAX_TARGET initialization parameters are both set to 0 (zero).

- The SGA_TARGET initialization parameter is set to a nonzero value.

The Streams pool size is the value specified by the STREAMS_POOL_SIZE parameter, in bytes, if the following conditions are met:

- The MEMORY_TARGET, MEMORY_MAX_TARGET, and SGA_TARGET initialization parameters are all set to 0 (zero).

- The STREAMS_POOL_SIZE initialization parameter is set to a nonzero value.

If you are using Automatic Shared Memory Management and the STREAMS_POOL_SIZE initialization parameter also is set to a nonzero value, then Automatic Shared Memory Management uses this value as a minimum for the Oracle Streams pool. You can set a minimum size if your environment needs a minimum amount of memory in the Oracle Streams pool to function properly. The current memory allocated to Oracle Streams pool by Automatic Shared Memory Management can be viewed by querying the V$SGA_DYNAMIC_COMPONENTS view. In addition, you can query the V$STREAMS_POOL_STATISTICS view to view the current usage of the Oracle Streams pool.

See Also:

- Oracle Database PL/SQL Packages and Types Reference for more information about the max_sga_size capture process parameter

- Oracle Database Administrator's Guide

- Oracle Database Reference

If Required, Configure Supplemental Logging

When you use a capture process to capture changes, supplemental logging must be specified for certain columns at a source database for changes to the columns to be applied successfully at a destination database. Supplemental logging places additional information in the redo log for these columns. A capture process captures this additional information and places it in logical change records (LCRs), and an XStream inbound server or client application might need this additional information to process changes properly.

This section contains these topics:

- Required Supplemental Logging in an XStream Environment

- Specifying Table Supplemental Logging Using Unconditional Log Groups

- Specifying Table Supplemental Logging Using Conditional Log Groups

- Dropping a Supplemental Log Group

- Specifying Database Supplemental Logging of Key Columns

- Dropping Database Supplemental Logging of Key Columns

- Procedures That Automatically Specify Supplemental Logging

Required Supplemental Logging in an XStream Environment

There are two types of supplemental logging: database supplemental logging and table supplemental logging. Database supplemental logging specifies supplemental logging for an entire database, while table supplemental logging enables you to specify log groups for supplemental logging of a particular table. If you use table supplemental logging, then you can choose between two types of log groups: unconditional log groups and conditional log groups.

Unconditional log groups log the before images of specified columns when the table is changed, regardless of whether the change affected any of the specified columns. Unconditional log groups are sometimes referred to as "always log groups." Conditional log groups log the before images of all specified columns only if at least one of the columns in the log group is changed.

Supplementing logging at the database level, unconditional log groups at the table level, and conditional log groups at the table level determine which old values are logged for a change.

If you plan to use one or more XStream inbound servers to apply LCRs captured by a capture process, then you must enable supplemental logging at the source database for the following types of columns in tables at the destination database:

- Any columns at the source database that are used in a primary key in tables for which changes are applied at a destination database must be unconditionally logged in a log group or by database supplemental logging of primary key columns.

- If the parallelism of any inbound server that will apply the changes is greater than 1, then any unique constraint column at a destination database that comes from multiple columns at the source database must be conditionally logged. Supplemental logging does not need to be specified if a unique constraint column comes from a single column at the source database.

- If the parallelism of any inbound server that will apply the changes is greater than 1, then any foreign key column at a destination database that comes from multiple columns at the source database must be conditionally logged. Supplemental logging does not need to be specified if the foreign key column comes from a single column at the source database.

- If the parallelism of any inbound server that will apply the changes is greater than 1, then any bitmap index column at a destination database that comes from multiple columns at the source database must be conditionally logged. Supplemental logging does not need to be specified if the bitmap index column comes from a single column at the source database.

- Any columns at the source database that are used as substitute key columns for an inbound server at a destination database must be unconditionally logged. You specify substitute key columns for a table using the SET_KEY_COLUMNS procedure in the DBMS_APPLY_ADM package.

- The columns specified in a column list for conflict resolution during apply must be conditionally logged if multiple columns at the source database are used in the column list at the destination database.

- Any columns at the source database that are used by a statement DML handler, change handler, procedure DML handler, or error handler at a destination database must be unconditionally logged.

- Any columns at the source database that are used by a rule or a rule-based transformation must be unconditionally logged.

- Any columns at the source database that are specified in a value dependency virtual dependency definition at a destination database must be unconditionally logged.

- If you specify row subsetting for a table at a destination database, then any columns at the source database that are in the destination table or columns at the source database that are in the subset condition must be unconditionally logged. You specify a row subsetting condition for an inbound server using the dml_condition parameter in the ADD_SUBSET_RULES procedure in the DBMS_XSTREAM_ADM package.

If you do not use supplemental logging for these types of columns at a source database, then changes involving these columns might not apply properly at a destination database.

Note:
Columns of the following data types cannot be part of a supplemental log group: LOB, LONG, LONG RAW, user-defined types (including object types, REFs, varrays, nested tables), and Oracle-supplied types (including Any types, XML types, spatial types, and media types).

Specifying Table Supplemental Logging Using Unconditional Log Groups

To specify an unconditional supplemental log group that only includes the primary key column(s) for a table, use an ALTER TABLE statement with the PRIMARY KEY option in the ADD SUPPLEMENTAL LOG DATA clause. For example, the following statement adds the primary key column of the hr.regions table to an unconditional log group with a system-generated name:

ALTER TABLE hr.regions ADD SUPPLEMENTAL LOG DATA (PRIMARY KEY) COLUMNS;

To specify an unconditional supplemental log group that includes all of the columns in a table, use an ALTER TABLE statement with the ALL option in the ADD SUPPLEMENTAL LOG DATA clause. For example, the following statement adds all of the columns in the hr.regions table to an unconditional log group with a system-generated name:

ALTER TABLE hr.regions ADD SUPPLEMENTAL LOG DATA (ALL) COLUMNS;

To specify an unconditional supplemental log group that contains columns that you select, use an ALTER TABLE statement with the ALWAYS specification for the ADD SUPPLEMENTAL LOG GROUP clause.These log groups can include key columns, if necessary.

For example, the following statement adds the department_id column and the manager_id column of the hr.departments table to an unconditional log group named log_group_dep_pk:

ALTER TABLE hr.departments ADD SUPPLEMENTAL LOG GROUP log_group_dep_pk
(department_id, manager_id) ALWAYS;

The ALWAYS specification makes this log group an unconditional log group.

Specifying Table Supplemental Logging Using Conditional Log Groups

You can use the following options in the ADD SUPPLEMENTAL LOG DATA clause of an ALTER TABLE statement:

- The FOREIGN KEY option creates a conditional log group that includes the foreign key column(s) in the table.

- The UNIQUE option creates a conditional log group that includes the unique key column(s) and bitmap index column(s) in the table.

If you specify multiple options in a single ALTER TABLE statement, then a separate conditional log group is created for each option.

For example, the following statement creates two conditional log groups:

ALTER TABLE hr.employees ADD SUPPLEMENTAL LOG DATA
(UNIQUE, FOREIGN KEY) COLUMNS;

One conditional log group includes the unique key columns and bitmap index columns for the table, and the other conditional log group includes the foreign key columns for the table. Both log groups have a system-generated name.

Note:
Specifying the UNIQUE option does not enable supplemental logging of bitmap join index columns.

To specify a conditional supplemental log group that includes any columns you choose to add, you can use the ADD SUPPLEMENTAL LOG GROUP clause in the ALTER TABLE statement. To make the log group conditional, do not include the ALWAYS specification.

For example, suppose the min_salary and max_salary columns in the hr.jobs table are included in a column list for conflict resolution at a destination database. The following statement adds the min_salary and max_salary columns to a conditional log group named log_group_jobs_cr:

ALTER TABLE hr.jobs ADD SUPPLEMENTAL LOG GROUP log_group_jobs_cr
(min_salary, max_salary);

Dropping a Supplemental Log Group

To drop a conditional or unconditional supplemental log group, use the DROP SUPPLEMENTAL LOG GROUP clause in the ALTER TABLE statement. For example, to drop a supplemental log group named log_group_jobs_cr, run the following statement:

ALTER TABLE hr.jobs DROP SUPPLEMENTAL LOG GROUP log_group_jobs_cr;

Specifying Database Supplemental Logging of Key Columns

You have the option of specifying supplemental logging for all primary key, unique key, bitmap index, and foreign key columns in a source database. You might choose this option if you configure a capture process to capture changes to an entire database. To specify supplemental logging for all primary key, unique key, bitmap index, and foreign key columns in a source database, issue the following SQL statement:

ALTER DATABASE ADD SUPPLEMENTAL LOG DATA
(PRIMARY KEY, UNIQUE, FOREIGN KEY) COLUMNS;

If your primary key, unique key, bitmap index, and foreign key columns are the same at all source and destination databases, then running this command at the source database provides the supplemental logging needed for primary key, unique key, bitmap index, and foreign key columns at all destination databases. When you specify the PRIMARY KEY option, all columns of a row's primary key are placed in the redo log file any time the table is modified (unconditional logging). When you specify the UNIQUE option, any columns in a row's unique key and bitmap index are placed in the redo log file if any column belonging to the unique key or bitmap index is modified (conditional logging). When you specify the FOREIGN KEY option, all columns of a row's foreign key are placed in the redo log file if any column belonging to the foreign key is modified (conditional logging).

You can omit one or more of these options. For example, if you do not want to supplementally log all of the foreign key columns in the database, then you can omit the FOREIGN KEY option, as in the following example:

ALTER DATABASE ADD SUPPLEMENTAL LOG DATA
(PRIMARY KEY, UNIQUE) COLUMNS;

In addition to PRIMARY KEY, UNIQUE, and FOREIGN KEY, you can also use the ALL option. The ALL option specifies that, when a row is changed, all the columns of that row (except for LOB, LONG, LONG RAW, user-defined type, and Oracle-supplied type columns) are placed in the redo log file (unconditional logging).

Supplemental logging statements are cumulative. If you issue two consecutive ALTER DATABASE ADD SUPPLEMENTAL LOG DATA statements, each with a different identification key, then both keys are supplementally logged.

Note:
Specifying the UNIQUE option does not enable supplemental logging of bitmap join index columns.

See Also:
Oracle Database SQL Language Reference for information about data types

Dropping Database Supplemental Logging of Key Columns

To drop supplemental logging for all primary key, unique key, bitmap index, and foreign key columns in a source database, issue the ALTER DATABASE DROP SUPPLEMENTAL LOG DATA statement. To drop database supplemental logging for all primary key, unique key, bitmap index, and foreign key columns, issue the following SQL statement:

ALTER DATABASE DROP SUPPLEMENTAL LOG DATA
(PRIMARY KEY, UNIQUE, FOREIGN KEY) COLUMNS;

Note:
Dropping database supplemental logging of key columns does not affect any existing table-level supplemental log groups.

Procedures That Automatically Specify Supplemental Logging

The following procedures in the DBMS_CAPTURE_ADM package automatically specify supplemental logging:

- BUILD

- PREPARE_GLOBAL_INSTANTIATION

- PREPARE_SCHEMA_INSTANTIATION

- PREPARE_TABLE_INSTANTIATION

The BUILD procedure automatically specifies database supplemental logging by running the ALTER DATABASE ADD SUPPLEMENTAL LOG DATA statement. In most cases, the BUILD procedure is run automatically when a capture process is created.

The PREPARE_GLOBAL_INSTANTIATION, PREPARE_SCHEMA_INSTANTIATION, and PREPARE_TABLE_INSTANTIATION procedures automatically specify supplemental logging of the primary key, unique key, bitmap index, and foreign key columns in the tables prepared for instantiation.

Certain procedures in the DBMS_XSTREAM_ADM package automatically run a procedure listed previously, including the ADD_SUBSET_RULES, ADD_TABLE_RULES, ADD_SCHEMA_RULES, and ADD_GLOBAL_RULES procedures.

See Also:
Oracle Database PL/SQL Packages and Types Reference for more information about these procedures

If Required, Configure Log File Transfer to a Downstream Database

If you decided to use a local capture process, then log file transfer is not required. However, if you decided to use downstream capture that uses redo transport services to transfer archived redo log files to the downstream database automatically, then configure log file transfer from the source database to the capture database. See "Decide How to Configure XStream Out" for information about this decision.

Tip:
You can use Oracle Enterprise Manager Cloud Control to configure log file transfer and a downstream capture process. See the Oracle Enterprise Manager Cloud Control online help for instructions.

The steps in this section configure the source database to transfer its redo log files to the capture database and configure the capture database to accept these redo log files.

To configure log file transfer to a downstream database:

1. Configure Oracle Net so that the source database can communicate with the downstream database.

See Also:
Oracle Database Net Services Administrator's Guide

2. Configure authentication at both databases to support the transfer of redo data.
Redo transport sessions are authenticated using either the Secure Sockets Layer (SSL) protocol or a remote login password file. If the source database has a remote login password file, then copy it to the appropriate directory on the downstream capture database system. The password file must be the same at the source database and the downstream capture database.

See Also:
Oracle Data Guard Concepts and Administration for detailed information about authentication requirements for redo transport

3. At the source database, set the following initialization parameters to configure redo transport services to transmit redo data from the source database to the downstream database:

- LOG_ARCHIVE_DEST_n - Configure at least one LOG_ARCHIVE_DEST_n initialization parameter to transmit redo data to the downstream database. Set the following attributes of this parameter in the following way:

- SERVICE - Specify the network service name of the downstream database.

- ASYNC or SYNC - Specify a redo transport mode.
The advantage of specifying ASYNC is that it results in little or no effect on the performance of the source database. ASYNC is recommended to avoid affecting source database performance if the downstream database or network is performing poorly.

The advantage of specifying SYNC is that redo data is sent to the downstream database faster then when ASYNC is specified. Also, specifying SYNC AFFIRM results in behavior that is similar to MAXIMUM AVAILABILITY standby protection mode. Note that specifying an ALTER DATABASE STANDBY DATABASE TO MAXIMIZE AVAILABILITY SQL statement has no effect on an XStream capture process.

- NOREGISTER - Specify this attribute so that the location of the archived redo log files is not recorded in the downstream database control file.

- VALID_FOR - Specify either (ONLINE_LOGFILE,PRIMARY_ROLE) or (ONLINE_LOGFILE,ALL_ROLES).

- TEMPLATE - If you are configuring an archived-log downstream capture process, then specify a directory and format template for archived redo logs at the downstream database. The TEMPLATE attribute overrides the LOG_ARCHIVE_FORMAT initialization parameter settings at the downstream database. The TEMPLATE attribute is valid only with remote destinations. Ensure that the format uses all of the following variables at each source database: %t, %s, and %r.
Do not specify the TEMPLATE attribute if you are configuring a real-time downstream capture process.

- DB_UNIQUE_NAME - The unique name of the downstream database. Use the name specified for the DB_UNIQUE_NAME initialization parameter at the downstream database.

The following example is a LOG_ARCHIVE_DEST_n setting that specifies the downstream database dbs2 for a real-time downstream capture process:

LOG_ARCHIVE_DEST_2='SERVICE=DBS2.EXAMPLE.COM ASYNC NOREGISTER
VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE)
DB_UNIQUE_NAME=dbs2'

The following example is a LOG_ARCHIVE_DEST_n setting that specifies the downstream database dbs2 for an archived-log downstream capture process:

LOG_ARCHIVE_DEST_2='SERVICE=DBS2.EXAMPLE.COM ASYNC NOREGISTER
VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE)
TEMPLATE=/usr/oracle/log_for_dbs1/dbs1_arch_%t_%s_%r.log
DB_UNIQUE_NAME=dbs2'

See "Decide How to Configure XStream Out" for information about the differences between real-time and archived-log downstream capture.

Tip:
If you are configuring an archived-log downstream capture process, then specify a value for the TEMPLATE attribute that keeps log files from a remote source database separate from local database log files. In addition, if the downstream database contains log files from multiple source databases, then the log files from each source database should be kept separate from each other.

- LOG_ARCHIVE_DEST_STATE_n - Set this initialization parameter that corresponds with the LOG_ARCHIVE_DEST_n parameter for the downstream database to ENABLE.
For example, if the LOG_ARCHIVE_DEST_2 initialization parameter is set for the downstream database, then set the LOG_ARCHIVE_DEST_STATE_2 parameter in the following way:

LOG_ARCHIVE_DEST_STATE_2=ENABLE

- LOG_ARCHIVE_CONFIG - Set the DB_CONFIG attribute in this initialization parameter to include the DB_UNIQUE_NAME of the source database and the downstream database.
For example, if the DB_UNIQUE_NAME of the source database is dbs1, and the DB_UNIQUE_NAME of the downstream database is dbs2, then specify the following parameter:

LOG_ARCHIVE_CONFIG='DG_CONFIG=(dbs1,dbs2)'

By default, the LOG_ARCHIVE_CONFIG parameter enables a database to both send and receive redo.

See Also:
Oracle Database Reference and Oracle Data Guard Concepts and Administration for more information about these initialization parameters

4. At the downstream database, set the DB_CONFIG attribute in the LOG_ARCHIVE_CONFIG initialization parameter to include the DB_UNIQUE_NAME of the source database and the downstream database.

For example, if the DB_UNIQUE_NAME of the source database is dbs1, and the DB_UNIQUE_NAME of the downstream database is dbs2, then specify the following parameter:

LOG_ARCHIVE_CONFIG='DG_CONFIG=(dbs1,dbs2)'

By default, the LOG_ARCHIVE_CONFIG parameter enables a database to both send and receive redo.

5. If you reset any initialization parameters while the instance was running at a database in Step 3 or Step 4, then you might want to reset them in the initialization parameter file as well, so that the new values are retained when the database is restarted.
If you did not reset the initialization parameters while the instance was running, but instead reset them in the initialization parameter file in Step 3 or Step 4, then restart the database. The source database must be open when it sends redo log files to the downstream database, because the global name of the source database is sent to the downstream database only if the source database is open.

When these steps are complete, you can add standby redo logs files at the downstream database if you want to configure a real-time downstream capture process. In this case, see the instructions in "If Required, Add Standby Redo Logs for Real-Time Downstream Capture".

If Required, Add Standby Redo Logs for Real-Time Downstream Capture

If you decided to configure real-time downstream capture, then add standby redo logs to the capture database. See "Decide How to Configure XStream Out" for information about this decision.

The example in this section adds standby redo logs at a downstream database. Standby redo logs are required to configure a real-time downstream capture process. In the example, the source database is dbs1.example.com and the downstream database is dbs2.example.com

The steps in this section are required only if you are configuring real-time downstream capture. If you are configuring archived-log downstream capture, then do not complete the steps in this section.

To add standby redo logs for real-time downstream capture:

1. Complete the steps in "If Required, Configure Log File Transfer to a Downstream Database".

2. At the downstream database, set the following initialization parameters to configure archiving of the redo data generated locally:

- Set at least one archive log destination in the LOG_ARCHIVE_DEST_n initialization parameter either to a directory or to the fast recovery area on the computer system running the downstream database. Set the following attributes of this parameter in the following way:

- LOCATION - Specify either a valid path name for a disk directory or, to use a fast recovery area, specify USE_DB_RECOVERY_FILE_DEST. This location is the local destination for archived redo log files written from the standby redo logs. Log files from a remote source database should be kept separate from local database log files. See Oracle Database Backup and Recovery User's Guide for information about configuring a fast recovery area.

- VALID_FOR - Specify either (ONLINE_LOGFILE,PRIMARY_ROLE) or (ONLINE_LOGFILE,ALL_ROLES).

The following example is a LOG_ARCHIVE_DEST_n setting for the locally generated redo data at the real-time downstream capture database:

LOG_ARCHIVE_DEST_1='LOCATION=/home/arc_dest/local_rl_dbs2
VALID_FOR=(ONLINE_LOGFILE,PRIMARY_ROLE)'

A real-time downstream capture configuration should keep archived standby redo log files separate from archived online redo log files generated by the downstream database. Specify ONLINE_LOGFILE instead of ALL_LOGFILES for the redo log type in the VALID_FOR attribute to accomplish this.

You can specify other attributes in the LOG_ARCHIVE_DEST_n initialization parameter if necessary.

- Set the LOG_ARCHIVE_DEST_STATE_n initialization parameter that corresponds with the LOG_ARCHIVE_DEST_n parameter previously set in this step to ENABLE.
For example, if the LOG_ARCHIVE_DEST_1 initialization parameter is set, then set the LOG_ARCHIVE_DEST_STATE_1 parameter in the following way:

LOG_ARCHIVE_DEST_STATE_1=ENABLE

3. At the downstream database, set the following initialization parameters to configure the downstream database to receive redo data from the source database and write the redo data to the standby redo log at the downstream database:

- Set at least one archive log destination in the LOG_ARCHIVE_DEST_n initialization parameter either to a directory or to the fast recovery area on the computer system running the downstream database. Set the following attributes of this parameter in the following way:

- LOCATION - Specify either a valid path name for a disk directory or, to use a fast recovery area, specify USE_DB_RECOVERY_FILE_DEST. This location is the local destination for archived redo log files written from the standby redo logs. Log files from a remote source database should be kept separate from local database log files. See Oracle Database Backup and Recovery User's Guide for information about configuring a fast recovery area.

- VALID_FOR - Specify either (STANDBY_LOGFILE,PRIMARY_ROLE) or (STANDBY_LOGFILE,ALL_ROLES).

The following example is a LOG_ARCHIVE_DEST_n setting for the redo data received from the source database at the real-time downstream capture database:

LOG_ARCHIVE_DEST_2='LOCATION=/home/arc_dest/srl_dbs1
VALID_FOR=(STANDBY_LOGFILE,PRIMARY_ROLE)'

You can specify other attributes in the LOG_ARCHIVE_DEST_n initialization parameter if necessary.

- Set the LOG_ARCHIVE_DEST_STATE_n initialization parameter that corresponds with the LOG_ARCHIVE_DEST_n parameter previously set in this step to ENABLE.
For example, if the LOG_ARCHIVE_DEST_2 initialization parameter is set for the downstream database, then set the LOG_ARCHIVE_DEST_STATE_2 parameter in the following way:

LOG_ARCHIVE_DEST_STATE_2=ENABLE

See Also:
Oracle Database Reference and Oracle Data Guard Concepts and Administration for more information about these initialization parameters

4. If you reset any initialization parameters while an instance was running at a database in Step 2 or Step 3, then you might want to reset them in the relevant initialization parameter file as well, so that the new values are retained when the database is restarted.
If you did not reset the initialization parameters while an instance was running, but instead reset them in the initialization parameter file in Step 2 or Step 3, then restart the database. The source database must be open when it sends redo data to the downstream database, because the global name of the source database is sent to the downstream database only if the source database is open.

5. Create the standby redo log files.

Note:
The following steps outline the general procedure for adding standby redo log files to the downstream database. The specific steps and SQL statements used to add standby redo log files depend on your environment. For example, in an Oracle Real Application Clusters (Oracle RAC) environment, the steps are different. See Oracle Data Guard Concepts and Administration for detailed instructions about adding standby redo log files to a database.

1. In SQL*Plus, connect to the source database dbs1.example.com as an administrative user.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Determine the log file size used on the source database. The standby log file size must exactly match (or be larger than) the source database log file size. For example, if the source database log file size is 500 MB, then the standby log file size must be 500 MB or larger. You can determine the size of the redo log files at the source database (in bytes) by querying the V$LOG view at the source database.
For example, query the V$LOG view:

SELECT BYTES FROM V$LOG;

3. Determine the number of standby log file groups required on the downstream database.
The number of standby log file groups must be at least one more than the number of online log file groups on the source database. For example, if the source database has two online log file groups, then the downstream database must have at least three standby log file groups.

You can determine the number of source database online log file groups by querying the V$LOG view of the source database for a single instance database or by querying the GV$LOG view for a database cluster.

For example, query the GV$LOG view:

SELECT COUNT(GROUP#) FROM GV$LOG;

4. In SQL*Plus, connect to the downstream database dbs2.example.com as an administrative user.

5. Use the SQL statement ALTER DATABASE ADD STANDBY LOGFILE to add the standby log file groups to the downstream database.
For example, assume that the source database has two online redo log file groups and is using a log file size of 500 MB. In this case, use the following statements to create the appropriate standby log file groups:

ALTER DATABASE ADD STANDBY LOGFILE GROUP 3
('/oracle/dbs/slog3a.rdo', '/oracle/dbs/slog3b.rdo') SIZE 500M;

ALTER DATABASE ADD STANDBY LOGFILE GROUP 4
('/oracle/dbs/slog4.rdo', '/oracle/dbs/slog4b.rdo') SIZE 500M;

ALTER DATABASE ADD STANDBY LOGFILE GROUP 5
('/oracle/dbs/slog5.rdo', '/oracle/dbs/slog5b.rdo') SIZE 500M;

6. Ensure that the standby log file groups were added successfully by running the following query:

SELECT GROUP#, THREAD#, SEQUENCE#, ARCHIVED, STATUS
FROM V$STANDBY_LOG;

You output should be similar to the following:

GROUP#    THREAD#  SEQUENCE# ARC STATUS
---------- ---------- ---------- --- ----------
3          0          0 YES UNASSIGNED
4          0          0 YES UNASSIGNED
5          0          0 YES UNASSIGNED

7. Ensure that log files from the source database are appearing in the location specified in the LOCATION attribute in Step 3. You might need to switch the log file at the source database to see files in the directory.

When these steps are complete, you are ready to configure a real-time downstream capture process.

Tip:
You can use Oracle Enterprise Manager Cloud Control to configure real-time downstream capture. See the Oracle Enterprise Manager Cloud Control online help for instructions.

Configuring XStream Out

An outbound server in an XStream Out configuration streams Oracle database changes to a client application. The client application attaches to the outbound server using the Oracle Call Interface (OCI) or Java interface to receive these changes.

Configuring an outbound server involves creating the components that send captured database changes to the outbound server. It also involves configuring the outbound server itself, which includes specifying the connect user that the client application will use to attach to the outbound server.

You can create an outbound server using the following procedures in the DBMS_XSTREAM_ADM package:

- The CREATE_OUTBOUND procedure creates an outbound server, a queue, and a capture process in a single database with one procedure call.

- The ADD_OUTBOUND procedure can create an outbound server, or it can add an outbound server to an existing XStream Out configuration. When you use this procedure on a database without an existing XStream Out configuration, it only creates an outbound server. You must create the capture process and queue separately, and they must exist before you run the ADD_OUTBOUND procedure. You can configure the capture process on the same database as the outbound server or on a different database.

In both cases, you must create the client application that communicates with the outbound server and receives LCRs from the outbound server.

If you require multiple outbound servers, then you can use the CREATE_OUTBOUND procedure to create the capture process that captures database changes for the first outbound server. Next, you can run the ADD_OUTBOUND procedure to add additional outbound servers that receive the same captured changes. The capture process can reside on the same database as the outbound servers or on a different database.

In addition, there are special considerations when you are configuring XStream Out in a CDB. This section provides instructions for creating outbound servers in a CDB.

Tip:
In an XStream Out configuration with multiple outbound servers, the best practice is to create one capture process that captures changes for all of the outbound servers.

This section contains these topics:

- Configuring an Outbound Server Using CREATE_OUTBOUND

- Adding an Additional Outbound Server to a Capture Process Stream

- Configuring an Outbound Server Using ADD_OUTBOUND

- Configuring XStream Out in a CDB

Configuring an Outbound Server Using CREATE_OUTBOUND

The CREATE_OUTBOUND procedure in the DBMS_XSTREAM_ADM package creates a capture process, queue, and outbound server in a single database. Both the capture process and the outbound server use the queue created by the procedure. When you run the procedure, you provide the name of the new outbound server, while the procedure generates a name for the capture process and queue. If you want all of the components to run on the same database, then the CREATE_OUTBOUND procedure is the fastest and easiest way to create an outbound server.

Prerequisites

Before configuring XStream Out, ensure that the following prerequisites are met:

- Complete the tasks described in "Prerequisites for Configuring XStream Out".

Assumptions

This section makes the following assumptions:

- The capture process will be a local capture process, and it will run on the same database as the outbound server.
The instructions in this section can only set up the local capture and outbound server on the same database configuration described in "Decide How to Configure XStream Out".

- The name of the outbound server is xout.

- Data manipulation language (DML) and data definition language (DDL) changes made to the oe.orders and oe.order_items tables are sent to the outbound server.

- DML and DDL changes made to the hr schema are sent to the outbound server.

Figure 4-5 provides an overview of this XStream Out configuration.

Figure 4-5 Sample XStream Out Configuration Created Using CREATE_OUTBOUND

To create an outbound server using the CREATE_OUTBOUND procedure:

1. In SQL*Plus, connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the CREATE_OUTBOUND procedure.

Given the assumptions for this section, run the following CREATE_OUTBOUND procedure:

DECLARE
tables  DBMS_UTILITY.UNCL_ARRAY;
schemas DBMS_UTILITY.UNCL_ARRAY;
BEGIN
tables(1)  := 'oe.orders';
tables(2)  := 'oe.order_items';
schemas(1) := 'hr';
DBMS_XSTREAM_ADM.CREATE_OUTBOUND(
server_name     =>  'xout',
table_names     =>  tables,
schema_names    =>  schemas);
END;
/

Running this procedure performs the following actions:

- Configures supplemental logging for the oe.orders and oe.order_items tables and for all of the tables in the hr schema.

- Creates a queue with a system-generated name that is used by the capture process and the outbound server.

- Creates and starts a capture process with a system-generated name with rule sets that instruct it to capture DML and DDL changes to the oe.orders table, the oe.order_items table, and the hr schema.

- Creates and starts an outbound server named xout with rule sets that instruct it to send DML and DDL changes to the oe.orders table, the oe.order_items table, and the hr schema to the client application.

- Sets the current user as the connect user for the outbound server. In this example, the current user is the XStream administrator. The client application must connect to the database as the connect user to interact with the outbound server.

Note:
The server_name value cannot exceed 30 bytes.

Tip:
To capture and send all database changes to the outbound server, specify NULL (the default) for the table_names and schema_names parameters.

3. Create and run the client application that will connect to the outbound server and receive the LCRs. See Appendix A, "Sample XStream Client Application" for a sample application.

4. To add one or more additional outbound servers that receive LCRs from the capture process created in Step 2, follow the instructions in "Adding an Additional Outbound Server to a Capture Process Stream".

When you run the client application, the outbound server is started automatically.

See Also:
Oracle Database PL/SQL Packages and Types Reference

Adding an Additional Outbound Server to a Capture Process Stream

XStream Out configurations often require multiple outbound servers that process a stream of LCRs from a single capture process. This section describes adding an additional outbound server to a database that already includes at least one outbound server. The additional outbound server uses the same queue as another outbound server to receive the LCRs from the capture process. When an XStream Out environment exists, use the ADD_OUTBOUND procedure in the DBMS_XSTREAM_ADM package to add another outbound server to a capture process stream.

Prerequisites

Before completing the steps in this section, configure an XStream Out environment that includes at least one outbound server. The following sections describe configuring and XStream Out environment:

- "Configuring an Outbound Server Using CREATE_OUTBOUND"

- "Configuring an Outbound Server Using ADD_OUTBOUND"

Assumptions

This section makes the following assumptions:

- The name of the outbound server is xout2.

- The queue used by the outbound server is xstrmadmin.xstream_queue.

- DML and DDL changes made to the oe.orders and oe.order_items tables are sent to the outbound server.

- DML and DDL changes made to the hr schema are sent to the outbound server.

- The source database for the database changes is db1.example.com.

Figure 4-6 provides an overview of this XStream Out configuration.

Figure 4-6 Sample XStream Out Configuration With an Additional Outbound Server

To add another outbound server to a capture process stream using the ADD_OUTBOUND procedure:

1. In SQL*Plus, connect to the database that will run the additional outbound server as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Determine the name of the queue used by an existing outbound server that receives LCRs from the capture process.
Run the query in "Displaying General Information About an Outbound Server" to determine the owner and name of the queue. This query also shows the name of the capture process and the source database name.

3. Run the ADD_OUTBOUND procedure.
Given the assumptions for this section, run the following ADD_OUTBOUND procedure:

DECLARE
tables  DBMS_UTILITY.UNCL_ARRAY;
schemas DBMS_UTILITY.UNCL_ARRAY;
BEGIN
tables(1)  := 'oe.orders';
tables(2)  := 'oe.order_items';
schemas(1) := 'hr';
DBMS_XSTREAM_ADM.ADD_OUTBOUND(
server_name     =>  'xout2',
queue_name      =>  'xstrmadmin.xstream_queue',
source_database =>  'db1.example.com',
table_names     =>  tables,
schema_names    =>  schemas);
END;
/

Running this procedure performs the following actions:

- Creates an outbound server named xout2. The outbound server has rule sets that instruct it to send DML and DDL changes to the oe.orders table, the oe.order_items table, and the hr schema to the client application. The rules specify that these changes must have originated at the db1.example.com database. The outbound server dequeues LCRs from the queue xstrmadmin.xstream_queue.

- Sets the current user as the connect user for the outbound server. In this example, the current user is the XStream administrator. The client application must connect to the database as the connect user to interact with the outbound server.

Note:
The server_name value cannot exceed 30 bytes.

Tip:
For the outbound server to receive all of the LCRs sent by the capture process, specify NULL (the default) for the table_names and schema_names parameters.

4. If a client application does not exist, then create and run the client application that will connect to the outbound server and receive the LCRs. See Appendix A, "Sample XStream Client Application" for a sample application.

When you run the client application, the outbound server is started automatically.

See Also:
Oracle Database PL/SQL Packages and Types Reference

Configuring an Outbound Server Using ADD_OUTBOUND

The ADD_OUTBOUND procedure in the DBMS_XSTREAM_ADM package creates an outbound server. This procedure does not create the capture process or the queue. In a database without an existing XStream Out configuration, you must configure these components manually.

You can use the ADD_OUTBOUND procedure to set up any of the configurations described in "Decide How to Configure XStream Out". However, if you chose to configure local capture and outbound server on the same database, then it is usually easier to use the CREATE_OUTBOUND procedure to configure all of the components simultaneously. See "Configuring an Outbound Server Using CREATE_OUTBOUND".

This section includes an example that configures downstream capture and the outbound server in the same database.

Prerequisites

Before configuring XStream Out, ensure that the following prerequisites are met:

- Complete the tasks described in "Prerequisites for Configuring XStream Out".
If you decide to use downstream capture, then you must configure log file transfer from the source database to a downstream database. See "If Required, Configure Log File Transfer to a Downstream Database".

If you want to use real-time downstream capture, then you must also add the required standby redo logs. See "If Required, Add Standby Redo Logs for Real-Time Downstream Capture".

The example in this section uses downstream capture. Therefore, log file transfer must be configured to complete the example.

Assumptions

This section makes the following assumptions:

- The name of the outbound server is xout.

- The queue used by the outbound server is xstrmadmin.xstream_queue.

- The source database is db1.example.com.

- The capture process and outbound server run on a different database than the source database. Therefore, downstream capture is configured.

- DML and DDL changes made to the oe.orders and oe.order_items tables are sent to the outbound server.

- DML and DDL changes made to the hr schema are sent to the outbound server.

Figure 4-7 provides an overview of this XStream Out configuration.

Figure 4-7 Sample XStream Out Configuration Created Using ADD_OUTBOUND

To create an outbound server using the ADD_OUTBOUND procedure:

1. In SQL*Plus, connect to the database that will run the capture process (the capture database) as the XStream administrator.

See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Create the queue that will be used by the capture process.
For example, run the following procedure:

BEGIN
DBMS_XSTREAM_ADM.SET_UP_QUEUE(
queue_table => 'xstrmadmin.xstream_queue_table',
queue_name  => 'xstrmadmin.xstream_queue');
END;
/

3. Create the database link from the downstream capture database to the source database.
In this example, create a database link from the downstream capture database to db1.example.com. For example, if the user xstrmadmin is the XStream administrator on both databases, then create the following database link:

CREATE DATABASE LINK db1.example.com CONNECT TO xstrmadmin
IDENTIFIED BY password USING 'db1.example.com';

See "If Required, Configure Network Connectivity and Database Links".

If you do not create the database link, then you must complete the following steps in source database:

1. Connect to the source database as the XStream administrator.

2. Run the DBMS_CAPTURE_ADM.BUILD procedure. For example:

SET SERVEROUTPUT ON
DECLARE
scn  NUMBER;
BEGIN
DBMS_CAPTURE_ADM.BUILD(
first_scn => scn);
DBMS_OUTPUT.PUT_LINE('First SCN Value = ' || scn);
END;
/
First SCN Value = 409391

This procedure displays the valid first SCN value for the capture process that will be created in the downstream capture database. Make a note of the SCN value returned because you will use it when you create the capture process in Step 4.

3. Ensure that required supplemental logging is specified for the database objects at the source database.
For this example, ensure that supplemental logging is configured for the hr schema, the oe.orders table, and the oe.order_items table in the db1.example.com database.

See "If Required, Configure Supplemental Logging" for instructions about specifying supplemental logging.

These steps are not required if you create the database link.

4. While connected to the downstream capture database, create the capture process and add rules to it.

For example, run the following procedure to create the capture process:

BEGIN
DBMS_CAPTURE_ADM.CREATE_CAPTURE(
queue_name         => 'xstrmadmin.xstream_queue',
capture_name       => 'xout_capture',
capture_class      => 'xstream');
END;
/

Add rules to the capture process's rule sets to capture changes to the hr schema, the oe.orders table, and the oe.order_items table.

For example, run the following procedures to create the rules:

BEGIN
DBMS_XSTREAM_ADM.ADD_SCHEMA_RULES(
schema_name     => 'hr',
streams_type    => 'capture',
streams_name    => 'xout_capture',
queue_name      => 'xstrmadmin.xstream_queue',
include_dml     => TRUE,
include_ddl     => TRUE,
source_database => 'db1.example.com');
END;
/

BEGIN
DBMS_XSTREAM_ADM.ADD_TABLE_RULES(
table_name      =>  'oe.orders',
streams_type    => 'capture',
streams_name    => 'xout_capture',
queue_name      => 'xstrmadmin.xstream_queue',
include_dml     => TRUE,
include_ddl     => TRUE,
source_database => 'db1.example.com');
END;
/

BEGIN
DBMS_XSTREAM_ADM.ADD_TABLE_RULES(
table_name      =>  'oe.order_items',
streams_type    => 'capture',
streams_name    => 'xout_capture',
queue_name      => 'xstrmadmin.xstream_queue',
include_dml     => TRUE,
include_ddl     => TRUE,
source_database => 'db1.example.com');
END;
/

Do not start the capture process.

5. Run the ADD_OUTBOUND procedure.
Given the assumption for this section, run the following ADD_OUTBOUND procedure:

DECLARE
tables  DBMS_UTILITY.UNCL_ARRAY;
schemas DBMS_UTILITY.UNCL_ARRAY;
BEGIN
tables(1)  := 'oe.orders';
tables(2)  := 'oe.order_items';
schemas(1) := 'hr';
DBMS_XSTREAM_ADM.ADD_OUTBOUND(
server_name     =>  'xout',
queue_name      =>  'xstrmadmin.xstream_queue',
source_database =>  'db1.example.com',
table_names     =>  tables,
schema_names    =>  schemas);
END;
/

Running this procedure performs the following actions:

- Creates an outbound server named xout. The outbound server has rule sets that instruct it to send DML and DDL changes to the oe.orders table, the oe.order_items table, and the hr schema to the client application. The rules specify that these changes must have originated at the db1.example.com database. The outbound server dequeues LCRs from the queue xstrmadmin.xstream_queue.

- Sets the current user as the connect user for the outbound server. In this example, the current user is the XStream administrator. The client application must connect to the database as the connect user to interact with the outbound server.

Note:
The server_name value cannot exceed 30 bytes.

Tip:
For the outbound server to receive all of the LCRs sent by the capture process, specify NULL (the default) for the table_names and schema_names parameters.

6. Create and run the client application that will connect to the outbound server and receive the LCRs. See Appendix A, "Sample XStream Client Application" for a sample application.
When you run the client application, the outbound server is started automatically.

7. To add one or more additional outbound servers that receive LCRs from the capture process created in Step 4, follow the instructions in "Adding an Additional Outbound Server to a Capture Process Stream".

See Also:
Oracle Database PL/SQL Packages and Types Reference

Configuring XStream Out in a CDB

Before you configure XStream Out in a CDB, you should review "XStream Out and a Multitenant Environment". When you configure XStream Out in a CDB, you must decide which database changes will be captured by XStream Out and sent to the client application. XStream Out can stream all of the database changes for all containers, including the root and all of the PDBs, or XStream Out can stream the changes from specific PDBs.

In addition, you can configure XStream Out with local capture, or you can configure it with downstream capture to offload the work required to capture changes from the source database.

The following restrictions apply when you configure XStream Out in a CDB:

- The capture process and outbound server must be in the root.

- The capture process and outbound server must be in the same CDB.

- Each PDB in the CDB must be open during XStream Out configuration.

In addition, ensure that you create the XStream administrator properly for a CDB.

The following sections describe configuring XStream Out in a CDB:

- Configuring XStream Out with Local Capture in a CDB

- Configuring XStream Out with Downstream Capture in CDBs

Note:
When a PDB is created using a non-CDB, any XStream Out components from the non-CDB cannot be used in the PDB. You must drop and recreate the XStream Out components, including the capture process and outbound servers, in the root of the CDB.

See Also:

- "XStream Out and a Multitenant Environment"

- "System-Created Rules in a CDB and XStream Out"

- "Configure an XStream Administrator on All Databases"

- Oracle Database Administrator's Guide for information about creating a PDB using a non-CDB

Configuring XStream Out with Local Capture in a CDB

This example shows the same XStream Out configuration as the example discussed in Figure 4-5. The only difference is that the database is a PDB within a CDB.

Prerequisites

Before configuring XStream Out, the following prerequisites must be met:

- Complete the tasks described in "Prerequisites for Configuring XStream Out".

- Ensure that all of the PDBs in the CDB are in open read/write mode during XStream Out configuration.

Assumptions

This section makes the following assumptions:

- The capture process will be a local capture process, and it will run on the same database as the outbound server.

- The name of the outbound server is xout.

- Data manipulation language (DML) and data definition language (DDL) changes made to the oe.orders and oe.order_items tables in PDB pdb1.example.com are sent to the outbound server.

- DML and DDL changes made to the hr schema in the PDB pdb1.example.com are sent to the outbound server.

Figure 4-8 provides an overview of this XStream Out configuration.

Figure 4-8 Sample XStream Out Configuration Created Using CREATE_OUTBOUND for a PDB

To create an outbound server using the CREATE_OUTBOUND procedure:

1. In SQL*Plus, connect to the root in the CDB (not to the PDB pdb1.example.com) as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a container in a CDB in SQL*Plus.

2. Create the outbound server and other XStream components.

1. Ensure that all of the PDBs in the source CDB are in open read/write mode.

2. Run the CREATE_OUTBOUND procedure.

Given the assumptions for this example, run the following CREATE_OUTBOUND procedure:

DECLARE
tables  DBMS_UTILITY.UNCL_ARRAY;
schemas DBMS_UTILITY.UNCL_ARRAY;
BEGIN
tables(1)  := 'oe.orders';
tables(2)  := 'oe.order_items';
schemas(1) := 'hr';
DBMS_XSTREAM_ADM.CREATE_OUTBOUND(
server_name     =>  'xout',
source_database =>  'pdb1.example.com',
table_names     =>  tables,
schema_names    =>  schemas);
END;
/

Note:
To capture changes in all containers in a CDB, including all PDBs and the root, and send those changes to the XStream client application, you can omit the source_database parameter when you run the CREATE_OUTBOUND procedure.

3. After the CREATE_OUTBOUND procedure completes successfully, optionally change the open mode of one or more PDBs if necessary.

Running the procedure in Step b performs the following actions:

- Configures supplemental logging for the oe.orders and oe.order_items tables and for all of the tables in the hr schema in the pdb1.example.com PDB.

- Creates a queue with a system-generated name that is used by the capture process and the outbound server.

- Creates and starts a capture process with a system-generated name with rule sets that instructs it to capture DML and DDL changes to the oe.orders table, the oe.order_items table, and the hr schema from the pdb1.example.com PDB.

- Creates and starts an outbound server named xout with rule sets that instruct it to send DML and DDL changes to the oe.orders table, the oe.order_items table, and the hr schema to the client application.

- Sets the current user as the connect user for the outbound server. In this example, the current user is the XStream administrator. The client application must connect to the database as the connect user to interact with the outbound server.

Note:
The server_name value cannot exceed 30 bytes.

Tip:
To capture and send all database changes from the pdb1.example.com database to the outbound server, specify NULL (the default) for the table_names and schema_names parameters.

3. Create and run the client application that will connect to the outbound server in the root of the CDB and receive the LCRs. See Appendix A, "Sample XStream Client Application" for a sample application.

When you run the client application, the outbound server is started automatically.

Configuring XStream Out with Downstream Capture in CDBs

Using downstream capture, the XStream Out components can be placed on different databases than the source database. When you have multiple CDBs, the source database can be in one CDB, and you can use downstream capture to capture the changes in another CDB.

Prerequisites

Before configuring XStream Out, the following prerequisites must be met:

- Complete the tasks described in "Prerequisites for Configuring XStream Out".

- Ensure that all of the PDBs in the CDB are in open read/write mode during XStream Out configuration.

- This example uses downstream capture. Therefore, you must configure log file transfer from the source database to a downstream database. See "If Required, Configure Log File Transfer to a Downstream Database".

If you want to use real-time downstream capture, then you must also add the required standby redo logs. See "If Required, Add Standby Redo Logs for Real-Time Downstream Capture".

Assumptions

This section makes the following assumptions:

- The name of the outbound server is xout.

- The queue used by the outbound server is c##xstrmadmin.xstream_queue.

- The source database is the PDB pdb1.example.com in the CDB data.example.com.

- The capture process runs in the CDB capture.example.com.

- The outbound server runs in the CDB capture.example.com.

- DML and DDL changes made to the oe.orders and oe.order_items tables from the PDB pdb1.example.com are sent to the outbound server.

- DML and DDL changes made to the hr schema from the PDB pdb1.example.com are sent to the outbound server.

Figure 4-9 provides an overview of this XStream Out configuration.

Figure 4-9 Sample XStream Out Configuration Using Multiple CDBs and Downstream Capture

To configure XStream Out with downstream capture in CDBs:

1. In SQL*Plus, connect to the root of the downstream capture CDB as the XStream administrator.
In this example. the downstream capture CDB is capture.example.com.

See Oracle Database Administrator's Guide for information about connecting to a container in a CDB in SQL*Plus.

2. Create the queue that will be used by the capture process.
For example, run the following procedure:

BEGIN
DBMS_XSTREAM_ADM.SET_UP_QUEUE(
queue_table => 'c##xstrmadmin.xstream_queue_table',
queue_name  => 'c##xstrmadmin.xstream_queue');
END;
/

3. Optionally, create the database link from the root in the downstream capture CDB to the root in the source CDB.

In this example, create a database link from the root in capture.example.com to the root in data.example.com. For example, if the user c##xstrmadmin is the XStream administrator on both databases, then create the following database link:

CREATE DATABASE LINK data.example.com CONNECT TO c##xstrmadmin
IDENTIFIED BY password USING 'data.example.com';

See "If Required, Configure Network Connectivity and Database Links".

4. Ensure that all of the PDBs in the source CDB are in open read/write mode.

5. If you did not create the database link in Step 3, then you must complete additional steps in the root of the source CDB.
These steps are not required if you created the database link in Step 3.

Run the BUILD procedure and ensure that required supplemental logging is specified for the database objects in the source CDB:

1. Connect to the root in the source CDB as the XStream administrator.

2. Run the DBMS_CAPTURE_ADM.BUILD procedure. For example:

SET SERVEROUTPUT ON
DECLARE
scn  NUMBER;
BEGIN
DBMS_CAPTURE_ADM.BUILD(
first_scn => scn);
DBMS_OUTPUT.PUT_LINE('First SCN Value = ' || scn);
END;
/
First SCN Value = 409391

This procedure displays the valid first SCN value for the capture process that will be created in the root in the capture.example.com CDB. Make a note of the SCN value returned because you will use it when you create the capture process in Step 6.

3. Ensure that required supplemental logging is specified for the database objects in the source CDB.
For this example, ensure that supplemental logging is configured for the hr schema, the oe.orders table, and the oe.order_items table in the pdb1.example.com PDB.

See "If Required, Configure Supplemental Logging" for instructions about specifying supplemental logging.

6. While connected to the root in the downstream capture CDB, create the capture process.

For example, run the following procedure to create the capture process while connected as the XStream administrator to capture.example.com:

BEGIN
DBMS_CAPTURE_ADM.CREATE_CAPTURE(
queue_name         => 'c##xstrmadmin.xstream_queue',
capture_name       => 'real_time_capture',
rule_set_name      => NULL,
start_scn          => NULL,
source_database    => NULL,
use_database_link  => TRUE,
first_scn          => NULL,
logfile_assignment => 'implicit',
source_root_name   => 'data.example.com',
capture_class      => 'xstream');
END;
/

If you did not create a database link in Step 3, then specify the SCN value returned by the DBMS_CAPTURE_ADM.BUILD procedure for the first_scn parameter.

Do not start the capture process.

7. After the capture process is created, optionally change the open mode of one or more PDBs if necessary.

8. Run the ADD_OUTBOUND procedure.
Given the assumption for this section, run the following ADD_OUTBOUND procedure:

DECLARE
tables  DBMS_UTILITY.UNCL_ARRAY;
schemas DBMS_UTILITY.UNCL_ARRAY;
BEGIN
tables(1)  := 'oe.orders';
tables(2)  := 'oe.order_items';
schemas(1) := 'hr';
DBMS_XSTREAM_ADM.ADD_OUTBOUND(
server_name           =>  'xout',
queue_name            =>  'c##xstrmadmin.xstream_queue',
source_database       =>  'pdb1.example.com',
table_names           =>  tables,
schema_names          =>  schemas,
source_root_name      => 'data.example.com',
source_container_name => 'pdb1');
END;
/

Running this procedure performs the following actions:

- Creates an outbound server named xout. The outbound server has rule sets that instruct it to send DML and DDL changes to the oe.orders table, the oe.order_items table, and the hr schema to the client application. The rules specify that these changes must have originated at the PDB pdb1.example.com in the CDB data.example.com. The outbound server dequeues LCRs from the queue c##xstrmadmin.xstream_queue.

- Sets the current user as the connect_user for the outbound server. In this example, the current_user is the XStream administrator. The client application must connect to the database as the connect_user to interact with the outbound server.

Note:
The server_name value cannot exceed 30 bytes.

9. Create and run the client application that will connect to the outbound server and receive the LCRs. See Appendix A, "Sample XStream Client Application" for a sample application.

When you run the client application, the outbound server is started automatically at the downstream capture CDB.

5 Managing XStream Out

This chapter provides instructions for managing XStream.

This chapter contains these topics:

- About Managing XStream Out

- Managing an Outbound Server

- Managing the Capture Process for an Outbound Server

- Managing Rules for an XStream Out Configuration

- Managing Declarative Rule-Based Transformations

- Dropping Components in an XStream Out Configuration

- Removing an XStream Out Configuration

About Managing XStream Out

This chapter describes managing an XStream Out configuration. This chapter provides instructions for modifying the database components that are part of an XStream Out configuration, such as outbound severs, capture processes, and rules.

The main interface for managing XStream Out database components is PL/SQL. Specifically, use the following Oracle supplied PL/SQL packages to manage XStream Out:

- DBMS_XSTREAM_ADM
The DBMS_XSTREAM_ADM package is the main package for managing XStream Out. This package includes subprograms that enable you to configure, modify, or drop outbound servers. This package also enables you modify the rules used by capture processes and outbound servers.

See Oracle Database PL/SQL Packages and Types Reference for detailed information about this package.

- DBMS_XSTREAM_AUTH
The DBMS_XSTREAM_AUTH package enables you to configure and modify XStream administrators.

See "Configure an XStream Administrator on All Databases" for information about using this package to create an XStream administrator. See Oracle Database PL/SQL Packages and Types Reference for detailed information about this package.

- DBMS_APPLY_ADM
The DBMS_APPLY_ADM package enables you modify outbound servers.

See Oracle Database PL/SQL Packages and Types Reference for detailed information about this package.

- DBMS_CAPTURE_ADM
The DBMS_CAPTURE_ADM package enables you configure and modify capture processes.

See Oracle Database PL/SQL Packages and Types Reference for detailed information about this package.

See Also:

- Chapter 3, "XStream Out Concepts"

- Chapter 4, "Configuring XStream Out"

- Chapter 6, "Monitoring XStream Out"

Managing an Outbound Server

This section describes managing an outbound server.

This section contains these topics:

- Starting an Outbound Server

- Stopping an Outbound Server

- Setting an Apply Parameter for an Outbound Server

- Changing the Connect User for an Outbound Server

Starting an Outbound Server

A outbound server must be enabled for it to send logical change records (LCRs) to an XStream client application. You run the START_OUTBOUND procedure in the DBMS_OUTBOUND_ADM package to start an existing outbound server.

To start an outbound server:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the START_OUTBOUND procedure in the DBMS_XSTREAM_ADM package, and specify the outbound server for the server_name parameter.

The following example starts a outbound server named xout.

Example 5-1 Starting an Outbound Server Named xout

BEGIN
DBMS_XSTREAM_ADM.START_OUTBOUND(
server_name => 'xout');
END;
/

Note:
When an XStream client application attaches to an outbound server, it starts the outbound server and the outbound server's capture process automatically if either of these components are disabled.

See Also:
The Oracle Enterprise Manager Cloud Control online help for instructions about starting an apply process or an outbound server with Oracle Enterprise Manager Cloud Control

Stopping an Outbound Server

You run the STOP_SERVER procedure in the DBMS_XSTREAM_ADM package to stop an existing outbound server. You might stop an outbound server when you are troubleshooting a problem in an XStream configuration.

To stop an outbound server:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the STOP_SERVER procedure in the DBMS_XSTREAM_ADM package, and specify the outbound server for the server_name parameter.

The following example stops a outbound server named xout.

Example 5-2 Stopping an Outbound Server Named xout

BEGIN
DBMS_XSTREAM_ADM.STOP_OUTBOUND(
server_name => 'xout');
END;
/

See Also:
The Oracle Enterprise Manager Cloud Control online help for instructions about stopping an apply process or an outbound server with Oracle Enterprise Manager Cloud Control

Setting an Apply Parameter for an Outbound Server

You set an apply parameter for an outbound server using the SET_PARAMETER procedure in the DBMS_XSTREAM_ADM package. Apply parameters control the way an outbound server operates.

To set an outbound server parameter:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the SET_PARAMETER procedure in the DBMS_XSTREAM_ADM package.

Note:

- The value parameter is always entered as a VARCHAR2 value, even if the parameter value is a number.

- If the value parameter is set to NULL or is not specified, then the parameter is set to its default value.

Example 5-3 Setting an Outbound Server Parameter

The following example sets the disable_on_error parameter for an outbound server named xout to N.

BEGIN
DBMS_XSTREAM_ADM.SET_PARAMETER(
streams_name => 'xout',
streams_type => 'apply'
parameter    => 'disable_on_error',
value        => 'N');
END;
/

Example 5-4 Setting an Outbound Server Parameter to Its Default Value

If the value parameter is set to NULL or is not specified, then the parameter is set to its default value. The following example sets the MAX_SGA_SIZE apply parameter to NULL:

BEGIN
DBMS_XSTREAM_ADM.SET_PARAMETER(
streams_name => 'xout',
streams_type => 'apply'
parameter  => 'max_sga_size',
value      => NULL);
END;
/

See Also:

- The Oracle Enterprise Manager Cloud Control online help for instructions about setting an apply parameter with Oracle Enterprise Manager Cloud Control

- Oracle Database PL/SQL Packages and Types Reference for information about apply parameters

Changing the Connect User for an Outbound Server

A client application connects to an outbound server as the connect user. This section describes changing the connect user for an outbound server using the ALTER_OUTBOUND procedure in the DBMS_XSTREAM_ADM package.

The connect user is the user who can attach to the outbound server to retrieve the LCR stream. The client application must attach to the outbound server as the connect user.

You can change the connect_user when a client application must connect to an outbound server as a different user. Ensure that the connect user is granted the required privileges.

Note:
The default connect_user is the user that configured the outbound server. If you want to run the client application as a different user, follow the steps outlined below.

To change the connect_user for an outbound server:

1. Connect to the outbound server database as the XStream administrator.
The XStream administrator must be granted the DBA role to change the connect user for an outbound server.

See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the ALTER_OUTBOUND procedure, and specify the following parameters:

- server_name - Specify the name of the outbound server.

- connect_user - Specify the new connect user.

Example 5-5 Changing the Connect User for an Outbound Server

To change the connect user to hr for an outbound server named xout, run the following procedure:

BEGIN
DBMS_XSTREAM_ADM.ALTER_OUTBOUND(
server_name  => 'xout',
connect_user => 'hr');
END;
/

See Also:

- "Privileges Required by the Connect User for an Outbound Server"

- Oracle Database PL/SQL Packages and Types Reference

Managing the Capture Process for an Outbound Server

This section describes managing the capture process for an outbound server. The capture process captures database changes and sends them to an outbound server.

This section contains these topics:

- Checking Whether the DBMS_XSTREAM_ADM Package Can Manage a Capture Process

- Starting a Capture Process

- Stopping a Capture Process

- Setting a Capture Process Parameter

- Changing the Capture User of an Outbound Server's Capture Process

- Changing the Start SCN or Start Time of an Outbound Server's Capture Process

- Setting the First SCN for a Capture Process

Checking Whether the DBMS_XSTREAM_ADM Package Can Manage a Capture Process

In some XStream Out configurations, you can use the DBMS_XSTREAM_ADM package to manage the capture process that captures changes for an outbound server. Even when you cannot use the DBMS_XSTREAM_ADM package, you can always use the DBMS_CAPTURE_ADM package to manage the capture process.

The DBMS_XSTREAM_ADM package can manage an outbound server's capture process if either of the following conditions are met:

- The capture process was created by the CREATE_OUTBOUND procedure in the DBMS_XSTREAM_ADM package.

- The queue used by the capture process was created by the CREATE_OUTBOUND procedure.

If either of these conditions are met, then the DBMS_XSTREAM_ADM package can manage an outbound server's capture process in the following ways:

- Add rules to and remove rules from the capture process's rule sets

- Change the capture user for the capture process

- Set the start system change number (SCN) or start time

- Drop the capture process

The DBMS_CAPTURE_ADM package can manage a capture process in the following ways:

- Start and stop the capture process

- Alter the capture process, which includes changing the capture process's rule sets, capture user, first SCN, start SCN, and start time

- Set capture process parameters

- Drop the capture process

To check whether an outbound server's capture process can be managed by the DBMS_XSTREAM_ADM package:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN SERVER_NAME HEADING 'Outbound Server Name' FORMAT A30
COLUMN CAPTURE_NAME HEADING 'Capture Process Name' FORMAT A30

SELECT SERVER_NAME,
CAPTURE_NAME
FROM ALL_XSTREAM_OUTBOUND;

Your output looks similar to the following:

Outbound Server Name           Capture Process Name
------------------------------ ------------------------------
XOUT                           CAP$_XOUT_4

If the Capture Process Name for an outbound server is non-NULL, then the DBMS_XSTREAM_ADM package can manage the capture process. In this case, you can also manage the capture process using the DBMS_CAPTURE_ADM package. However, it is usually better to manage the capture process for an outbound server using the DBMS_XSTREAM_ADM package when it is possible.

If the Capture Process Name for an outbound server is NULL, then the DBMS_XSTREAM_ADM package cannot manage the capture process. In this case, you must manage the capture process using the DBMS_CAPTURE_ADM package.

See Also:

- "Managing Rules for an XStream Out Configuration"

- "Changing the Capture User of an Outbound Server's Capture Process"

- "Changing the Start SCN or Start Time of an Outbound Server's Capture Process"

- "Dropping Components in an XStream Out Configuration"

- Oracle Database Reference

- Oracle Database PL/SQL Packages and Types Reference

Starting a Capture Process

A capture process must be enabled for it to capture database changes and send the changes to an XStream outbound server. You run the START_CAPTURE procedure in the DBMS_CAPTURE_ADM package to start an existing capture process.

To start a capture process:

1. Connect to the capture process database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the START_CAPTURE procedure in the DBMS_CAPTURE_ADM package, and specify the capture process for the capture_name parameter.

The following example starts a capture process named xstream_capture.

Example 5-6 Starting a Capture Process Named xstream_capture

BEGIN
DBMS_CAPTURE_ADM.START_CAPTURE(
capture_name => 'xstream_capture');
END;
/

Note:
When an XStream client application attaches to an outbound server, it starts the outbound server's capture process automatically if the capture process is disabled.

See Also:
The Oracle Enterprise Manager Cloud Control online help for instructions about starting a capture process with Oracle Enterprise Manager Cloud Control

Stopping a Capture Process

You run the STOP_CAPTURE procedure in the DBMS_CAPTURE_ADM package to stop an existing capture process. You might stop a capture process when you are troubleshooting a problem in an XStream configuration.

To stop a capture process:

1. Connect to the capture process database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the STOP_CAPTURE procedure in the DBMS_CAPTURE_ADM package, and specify the capture process for the capture_name parameter.

The following example starts a capture process named xstream_capture.

Example 5-7 Stopping a Capture Process Named xstream_capture

BEGIN
DBMS_CAPTURE_ADM.STOP_CAPTURE(
capture_name => 'xstream_capture');
END;
/

See Also:
The Oracle Enterprise Manager Cloud Control online help for instructions about stopping a capture process with Oracle Enterprise Manager Cloud Control

Setting a Capture Process Parameter

You set a capture process parameter using the SET_PARAMETER procedure in the DBMS_CAPTURE_ADM package. Capture process parameters control the way a capture process operates.

To set a capture process parameter:

1. Connect to the capture process database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the SET_PARAMETER procedure in the DBMS_CAPTURE_ADM package.

The following example sets the parallelism parameter for a capture process named xstream_capture to 1 from the default value of 0. The parallelism parameter controls the number of processes that concurrently mine the redo log for changes. It is a good idea to monitor the effect of increasing the parallelism for the capture process since additional processes are started.

Example 5-8 Setting a Capture Process Parameter

BEGIN
DBMS_CAPTURE_ADM.SET_PARAMETER(
capture_name => 'xstream_capture',
parameter    => 'parallelism',
value        => '1');
END;
/

Note:

- Setting the parallelism parameter automatically stops and restarts a capture process.

- The value parameter is always entered as a VARCHAR2 value, even if the parameter value is a number.

- If the value parameter is set to NULL or is not specified, then the parameter is set to its default value.

See Also:

- The Oracle Enterprise Manager Cloud Control online help for instructions about setting a capture process parameter with Oracle Enterprise Manager Cloud Control

- Oracle Database PL/SQL Packages and Types Reference for information about capture process parameters

Changing the Capture User of an Outbound Server's Capture Process

A capture user is the user in whose security domain a capture process captures changes from the redo log. This section describes changing the capture user for a capture process that captures changes for an outbound server using the ALTER_OUTBOUND procedure in the DBMS_XSTREAM_ADM package.

You can change the capture user when the capture process must capture changes in a different security domain. Only a user granted DBA role can change the capture user for a capture process. Ensure that the capture user is granted the required privileges. When you change the capture user, the ALTER_OUTBOUND procedure grants the new capture user enqueue privilege on the queue used by the capture process and configures the user as a secure queue user.

Note:
If Oracle Database Vault is installed, then the user who changes the capture user must be granted the BECOME USER system privilege. Granting this privilege to the user is not required if Oracle Database Vault is not installed. You can revoke the BECOME USER system privilege from the user after capture user is changed, if necessary.

See Also:
Oracle Database PL/SQL Packages and Types Reference for information about the privileges required by a capture user

To change the capture user of the capture process for an outbound server:

1. Determine whether the DBMS_XSTREAM_ADM package can manage the capture process. See "Checking Whether the DBMS_XSTREAM_ADM Package Can Manage a Capture Process".
Based on the check, follow the appropriate instructions:

- If the capture process can be managed using the DBMS_XSTREAM_ADM package, then proceed to Step 2.

- If the capture process cannot be managed using the DBMS_XSTREAM_ADM package, then follow the instructions in Oracle Streams Concepts and Administration.

2. Connect to the outbound server database as the XStream administrator.

To change the capture user, the user who invokes the ALTER_OUTBOUND procedure must be granted DBA role. Only the SYS user can set the capture user to SYS.

See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

3. Run the ALTER_OUTBOUND procedure, and specify the following parameters:

- server_name - Specify the name of the outbound server.

- capture_user - Specify the new capture user.

Example 5-9 Changing the Capture User of the Capture Process for an Outbound Server

To change the capture user to hq_admin for an outbound server named xout, run the following procedure:

BEGIN
DBMS_XSTREAM_ADM.ALTER_OUTBOUND(
server_name  => 'xout',
capture_user => 'hq_admin');
END;
/

See Also:
Oracle Database PL/SQL Packages and Types Reference

Changing the Start SCN or Start Time of an Outbound Server's Capture Process

This section describes changing the start system change number (SCN) or start time for a capture process that captures changes for an outbound server using the ALTER_OUTBOUND procedure in the DBMS_XSTREAM_ADM package.

The start SCN is the SCN from which a capture process begins to capture changes. The start time is the time from which a capture process begins to capture changes. When you reset a start SCN or start time for a capture process, ensure that the required redo log files are available to the capture process.

Typically, you reset the start SCN or start time for a capture process if point-in-time recovery was performed on one of the destination databases that receive changes from the capture process.

This section contains these topics:

- Changing the Start SCN of an Outbound Server's Capture Process

- Changing the Start Time of an Outbound Server's Capture Process

Note:

- The start_scn and start_time parameters in the ALTER_OUTBOUND procedure are mutually exclusive.

- You do not need to set the start SCN for a capture process after a normal restart of the database.

Changing the Start SCN of an Outbound Server's Capture Process

This section describes changing the start SCN of the capture process for an outbound server.

To change the start SCN for a capture process:

1. Determine whether the DBMS_XSTREAM_ADM package can manage the capture process. See "Checking Whether the DBMS_XSTREAM_ADM Package Can Manage a Capture Process".
Based on the check, follow the appropriate instructions:

- If the capture process can be managed using the DBMS_XSTREAM_ADM package, then proceed to Step 2.

- If the capture process cannot be managed using the DBMS_XSTREAM_ADM package, then follow the instructions in Oracle Streams Concepts and Administration.

2. Connect to the outbound server database as the XStream administrator.

See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

3. Check the first SCN of the capture process:

COLUMN CAPTURE_PROCESS HEADING 'Capture Process Name' FORMAT A30
COLUMN FIRST_SCN HEADING 'First SCN' FORMAT 99999999999999

SELECT CAPTURE_NAME, FIRST_SCN FROM ALL_CAPTURE;

CAPTURE_NAME                         First SCN
------------------------------ ---------------
CAP$_XOUT_1                             604426

When you reset the start SCN, the specified start SCN must be equal to or greater than the first SCN for the capture process.

4. Run the ALTER_OUTBOUND procedure, and specify the following parameters:

- server_name - Specify the name of the outbound server.

- start_scn - Specify the SCN from which the capture process begins to capture changes.

If the capture process is enabled, then the ALTER_OUTBOUND procedure automatically stops and restarts the capture process when the start_scn parameter is non-NULL.

If the capture process is disabled, then the ALTER_OUTBOUND procedure automatically starts the capture process when the start_scn parameter is non-NULL.

Example 5-10 Setting the Start SCN of the Capture Process for an Outbound Server

Run the following procedure to set the start SCN to 650000 for the capture process used by the xout outbound server:

BEGIN
DBMS_XSTREAM_ADM.ALTER_OUTBOUND(
server_name => 'xout',
start_scn    => 650000);
END;
/

See Also:

- Oracle Database PL/SQL Packages and Types Reference

- "SCN Values Related to a Capture Process"

Changing the Start Time of an Outbound Server's Capture Process

This section describes changing the start time of the capture process for an outbound server.

To change the start time for a capture process:

1. Determine whether the DBMS_XSTREAM_ADM package can manage the capture process. See "Checking Whether the DBMS_XSTREAM_ADM Package Can Manage a Capture Process".
Based on the check, follow the appropriate instructions:

- If the capture process can be managed using the DBMS_XSTREAM_ADM package, then proceed to Step 2.

- If the capture process cannot be managed using the DBMS_XSTREAM_ADM package, then follow the instructions in Oracle Streams Concepts and Administration.

2. Connect to the outbound server database as the XStream administrator.

See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

3. Check the time that corresponds with the first SCN of the capture process:

COLUMN CAPTURE_PROCESS HEADING 'Capture Process Name' FORMAT A30
COLUMN FIRST_SCN HEADING 'First SCN' FORMAT A40

SELECT CAPTURE_NAME, SCN_TO_TIMESTAMP(FIRST_SCN) FIRST_SCN FROM ALL_CAPTURE;

CAPTURE_NAME                   First SCN
------------------------------ ----------------------------------------
CAP$_XOUT_1                    05-MAY-10 08.11.17.000000000 AM

When you reset the start time, the specified start time must be greater than or equal to the time that corresponds with the first SCN for the capture process.

4. Run the ALTER_OUTBOUND procedure, and specify the following parameters:

- server_name - Specify the name of the outbound server.

- start_time - Specify the time from which the capture process begins to capture changes.

If the capture process is enabled, then the ALTER_OUTBOUND procedure automatically stops and restarts the capture process when the start_time parameter is non-NULL.

If the capture process is disabled, then the ALTER_OUTBOUND procedure automatically starts the capture process when the start_time parameter is non-NULL.

The following examples set the start_time parameter for the capture process that captures changes for an outbound server named xout.

Example 5-11 Set the Start Time to a Specific Time

Run the following procedure to set the start time to 05-MAY-10 11.11.17 AM for the capture process used by the xout outbound server:

BEGIN
DBMS_XSTREAM_ADM.ALTER_OUTBOUND(
server_name => 'xout',
start_time  => '05-MAY-10 11.11.17 AM');
END;
/

Example 5-12 Set the Start Time Using the NUMTODSINTERVAL SQL Function

Run the following procedure to set the start time to four hours earlier than the current time for the capture process used by the xout outbound server:

DECLARE
ts  TIMESTAMP;
BEGIN
ts := SYSTIMESTAMP - NUMTODSINTERVAL(4, 'HOUR');
DBMS_XSTREAM_ADM.ALTER_OUTBOUND(
server_name => 'xout',
start_time  => ts);
END;
/

See Also:

- Oracle Database PL/SQL Packages and Types Reference

- "SCN Values Related to a Capture Process"

Setting the First SCN for a Capture Process

You can set the first system change number (SCN) for an existing capture process. The first SCN is the SCN in the redo log from which a capture process can capture changes.

The specified first SCN must meet the following requirements:

- It must be greater than the current first SCN for the capture process.

- It must be less than or equal to the current applied SCN for the capture process. However, this requirement does not apply if the current applied SCN for the capture process is zero.

- It must be less than or equal to the required checkpoint SCN for the capture process.

You can determine the current first SCN, applied SCN, and required checkpoint SCN for each capture process in a database using the following query:

SELECT CAPTURE_NAME, FIRST_SCN, APPLIED_SCN, REQUIRED_CHECKPOINT_SCN   FROM ALL_CAPTURE;

When you reset a first SCN for a capture process, information below the new first SCN setting is purged from the LogMiner data dictionary for the capture process automatically. Therefore, after the first SCN is reset for a capture process, the start SCN for the capture process cannot be set lower than the new first SCN. Also, redo log files that contain information before the new first SCN setting will never be needed by the capture process.

You set the first SCN for a capture process using the ALTER_CAPTURE procedure in the DBMS_CAPTURE_ADM package.

To set the first SCN for a capture process:

1. Connect to the capture process database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the ALTER_CAPTURE procedure in the DBMS_CAPTURE_ADM package, and specify the new first SCN in the first_scn parameter.

The following example sets the first SCN to 351232 for the xstream_capture capture process.

Example 5-13 Setting the First SCN for a Capture Process

BEGIN
DBMS_CAPTURE_ADM.ALTER_CAPTURE(
capture_name => 'xstream_capture',
first_scn    => 351232);
END;
/

Note:

- If the specified first SCN is higher than the current start SCN for the capture process, then the start SCN is set automatically to the new value of the first SCN.

- If you must capture changes in the redo log from a point in time in the past, then you can create a capture process and specify a first SCN that corresponds to a previous data dictionary build in the redo log. The BUILD procedure in the DBMS_CAPTURE_ADM package performs a data dictionary build in the redo log.

- You can query the DBA_LOGMNR_PURGED_LOG data dictionary view to determine which redo log files will never be needed by any capture process.

See Also:
"SCN Values Related to a Capture Process"

Managing Rules for an XStream Out Configuration

This section describes managing rules for an XStream Out configuration. Rules control which database changes are streamed to the outbound server and which database changes the outbound server streams to the client application.

This section contains these topics:

- Adding Rules to an XStream Out Configuration

- Removing Rules from an XStream Out Configuration

Adding Rules to an XStream Out Configuration

This section describes adding schema rules, table rules, and subset rules to an XStream Out configuration.

This section contains these topics:

- Adding Schema Rules and Table Rules to an XStream Out Configuration

- Adding Subset Rules to an Outbound Server's Positive Rule Set

- Adding Rules With Custom Conditions to XStream Out Components

Adding Schema Rules and Table Rules to an XStream Out Configuration

This section describes adding schema rules and table rules to an XStream Out configuration using the ALTER_OUTBOUND procedure in the DBMS_XSTREAM_ADM package. The ALTER_OUTBOUND procedure adds rules for both data manipulation language (DML) and data definition language (DDL) changes.

When you follow the instructions in this section, the ALTER_OUTBOUND procedure always adds rules for the specified schemas and tables to one of the outbound server's rule sets. If the DBMS_XSTREAM_ADM package can manage the outbound server's capture process, then the ALTER_OUTBOUND procedure also adds rules for the specified schemas and tables to one of the rule sets used by this capture process.

To determine whether the DBMS_XSTREAM_ADM package can manage the outbound server's capture process, see "Checking Whether the DBMS_XSTREAM_ADM Package Can Manage a Capture Process". If the DBMS_XSTREAM_ADM package cannot manage the outbound server's capture process, then the ALTER_OUTBOUND procedure adds rules to the outbound server's rule set only. In this case, if rules for same schemas and tables should be added to the capture process's rule set as well, then use the ADD_*_RULES procedures in the DBMS_XSTREAM_ADM package to add them.

In addition, if the capture process is running on a different database than the outbound server, then add schema and table rules to the propagation that sends logical change records (LCRs) to the outbound server's database. Use the ADD_*_PROPAGATION_RULES procedures in the DBMS_XSTREAM_ADM package to add them.

To add schema rules and table rules to an XStream Out configuration:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the ALTER_OUTBOUND procedure, and specify the following parameters:

- server_name - Specify the name of the outbound server.

- table_names - Specify the tables for which to add rules, or specify NULL to add no table rules.

- schema_name - Specify the schemas for which to add rules, or specify NULL to add no schema rules.

- add - Specify TRUE so that the rules are added. (Rules are removed if you specify FALSE.)

- inclusion_rule - Specify TRUE to add rules to the positive rule set of the outbound server, or specify FALSE to add rules to the negative rule set of the outbound server. If the DBMS_XSTREAM_ADM package can manage the outbound server's capture process, then rules are also added to this capture process's rule set.

The following examples add rules to the configuration of an outbound server named xout.

Example 5-14 Adding Rules for the hr Schema, oe.orders Table, and oe.order_items Table to the Positive Rule Set

BEGIN
DBMS_XSTREAM_ADM.ALTER_OUTBOUND(
server_name    => 'xout',
table_names    => 'oe.orders, oe.order_items',
schema_names   => 'hr',
add            => TRUE,
inclusion_rule => TRUE);
END;
/

Example 5-15 Adding Rules for the hr Schema to the Negative Rule Set

BEGIN
DBMS_XSTREAM_ADM.ALTER_OUTBOUND(
server_name    => 'xout',
table_names    => NULL,
schema_names   => 'hr',
add            => TRUE,
inclusion_rule => FALSE);
END;
/

See Also:

- "Rules and Rule Sets"

- Oracle Database PL/SQL Packages and Types Reference

- Oracle Streams Concepts and Administration for more information about managing rules for a capture process

Adding Subset Rules to an Outbound Server's Positive Rule Set

This section describes adding subset rules to an outbound server's positive rule set using the ADD_SUBSET_OUTBOUND_RULES procedure in the DBMS_XSTREAM_ADM package. The ADD_SUBSET_OUTBOUND_RULES procedure only adds rules for DML changes to an outbound server's positive rule set. It does not add rules for DDL changes, and it does not add rules to a capture process's rule set.

To add subset rules to an outbound server's positive rule set:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the ADD_SUBSET_OUTBOUND_RULES procedure, and specify the following parameters:

- server_name - Specify the name of the outbound server.

- table_name - Specify the table for which you want to capture and stream a subset of data.

- condition - Specify the subset condition, which is similar to the WHERE clause in a SQL statement, to stream changes to a subset of rows in the table.

- column_list - Specify the subset of columns to keep or discard, or specify NULL to keep all of the columns.

- keep - Specify TRUE to keep the columns listed in the column_list parameter, or specify FALSE to discard the columns in the column_list parameter.

When column_list is non-NULL and keep is set to TRUE, the procedure creates a keep columns declarative rule-based transformation for the columns listed in column_list.

When column_list is non-NULL and keep is set to FALSE, the procedure creates a delete column declarative rule-based transformation for each column listed in column_list.

3. If subset rules should also be added to the rule set of a capture process or propagation that streams row LCRs to the outbound server, then use the ADD_*_RULES procedures in the DBMS_XSTREAM_ADM package to add them.

Example 5-16 Adding Rules That Stream Changes to a Subset of Rows in a Table

The following procedure creates rules that only evaluate to TRUE for row changes where the department_id value is 40 in the hr.employees table:

DECLARE
cols DBMS_UTILITY.LNAME_ARRAY;
BEGIN
cols(1) := 'employee_id';
cols(2) := 'first_name';
cols(3) := 'last_name';
cols(4) := 'email';
cols(5) := 'phone_number';
cols(6) := 'hire_date';
cols(7) := 'job_id';
cols(8) := 'salary';
cols(9) := 'commission_pct';
cols(10) := 'manager_id';
cols(11) := 'department_id';
DBMS_XSTREAM_ADM.ADD_SUBSET_OUTBOUND_RULES(
server_name => 'xout',
table_name  => 'hr.employees',
condition   => 'department_id=40',
column_list => cols);
END;
/

Example 5-17 Adding Rules That Stream Changes to a Subset of Rows and Columns in a Table

The following procedure creates rules that only evaluate to TRUE for row changes where the department_id value is 40 for the hr.employees table. The procedure also creates delete column declarative rule-based transformations for the salary and commission_pct columns.

BEGIN
DBMS_XSTREAM_ADM.ADD_SUBSET_OUTBOUND_RULES(
server_name => 'xout',
table_name  => 'hr.employees',
condition   => 'department_id=40',
column_list => 'salary,commission_pct',
keep        => FALSE);
END;
/

See Also:

- "Rules and Rule Sets"

- Oracle Database PL/SQL Packages and Types Reference

- "Declarative Rule-Based Transformations"

Adding Rules With Custom Conditions to XStream Out Components

Some of the procedures that create rules in the DBMS_XSTREAM_ADM package include an and_condition parameter. This parameter enables you to add conditions to system-created rules. The condition specified by the and_condition parameter is appended to the system-created rule condition using an AND clause in the following way:

(system_condition) AND (and_condition)

The variable in the specified condition must be :lcr.

To add a rule with a custom condition to an XStream Out component:

1. Connect to the database running the XStream Out component as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run an ADD_*_RULES procedure and specify the custom condition in the and_condition parameter.
See "System-Created Rules and XStream" for information about these procedures.

Example 5-18 Adding a Table Rule With a Custom Condition

This example specifies that the table rules generated by the ADD_TABLE_RULES procedure evaluate to TRUE only if the table is hr.departments, the source database is dbs1.example.com, and the tag value is the hexadecimal equivalent of '02'.

BEGIN
DBMS_XSTREAM_ADM.ADD_TABLE_RULES(
table_name          =>  'hr.departments',
streams_type        =>  'capture',
streams_name        =>  'xout_capture',
queue_name          =>  'xstream_queue',
include_dml         =>  TRUE,
include_ddl         =>  TRUE,
include_tagged_lcr  =>  TRUE,
source_database     =>  'dbs1.example.com',
inclusion_rule      =>  TRUE,
and_condition       =>  ':lcr.get_tag() = HEXTORAW(''02'')');
END;
/

If you are specifying an LCR member subprogram that is dependent on the LCR type (row or DDL), then ensure that this procedure only generates the appropriate rule. Specifically, if you specify an LCR member subprogram that is valid only for row LCRs, then specify TRUE for the include_dml parameter and FALSE for the include_ddl parameter. If you specify an LCR member subprogram that is valid only for DDL LCRs, then specify FALSE for the include_dml parameter and TRUE for the include_ddl parameter.

For example, the GET_OBJECT_TYPE member function only applies to DDL LCRs. Therefore, if you use this member function in an and_condition, then specify FALSE for the include_dml parameter and TRUE for the include_ddl parameter.

See Also:

- Oracle Database PL/SQL Packages and Types Reference for more information about LCR member subprograms

- Oracle Streams Replication Administrator's Guide for information about tags

Removing Rules from an XStream Out Configuration

This section describes removing rules from an XStream Out configuration.

This section contains these topics:

- Removing Schema Rules and Table Rules From an XStream Out Configuration

- Removing Subset Rules from an Outbound Server's Positive Rule Set

- Removing Rules Using the REMOVE_RULE Procedure

Removing Schema Rules and Table Rules From an XStream Out Configuration

This section describes removing schema rules and table rules from an XStream Out configuration using the ALTER_OUTBOUND procedure in the DBMS_XSTREAM_ADM package. The ALTER_OUTBOUND procedure removes rules for both DML and DDL changes.

When you follow the instructions in this section, the ALTER_OUTBOUND procedure always removes rules for the specified schemas and tables from one of the outbound server's rule sets. If the DBMS_XSTREAM_ADM package can manage the outbound server's capture process, then the ALTER_OUTBOUND procedure also removes rules for the specified schemas and tables from one of the rule sets used by this capture process.

To determine whether the DBMS_XSTREAM_ADM package can manage the outbound server's capture process, see "Checking Whether the DBMS_XSTREAM_ADM Package Can Manage a Capture Process". If the DBMS_XSTREAM_ADM package cannot manage the outbound server's capture process, then the ALTER_OUTBOUND procedure removes rules from the outbound server's rule set only. In this case, if you must remove the rules for same schemas and tables from the capture process's rule set as well, then see "Removing Rules Using the REMOVE_RULE Procedure" for instructions.

In addition, if the capture process is running on a different database than the outbound server, then remove the schema and table rules from the propagation that sends LCRs to the outbound server's database. See "Removing Rules Using the REMOVE_RULE Procedure" for instructions.

To remove schema rules and table rules from an XStream Out configuration:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the ALTER_OUTBOUND procedure, and specify the following parameters:

- server_name - Specify the name of the outbound server.

- table_names - Specify the tables for which to remove rules, or specify NULL to remove no table rules.

- schema_name - Specify the schemas for which to remove rules, or specify NULL to remove no schema rules.

- add - Specify FALSE so that the rules are removed. (Rules are added if you specify TRUE.)

- inclusion_rule - Specify TRUE to remove rules from the positive rule set of the outbound server, or specify FALSE to remove rules from the negative rule set of the outbound server. If the DBMS_XSTREAM_ADM package can manage the outbound server's capture process, then rules are also removed from this capture process's rule set.

The following examples remove rules from the configuration of an outbound server named xout.

Example 5-19 Removing Rules for the hr Schema, oe.orders Table, and oe.order_items Table from the Positive Rule Set

BEGIN
DBMS_XSTREAM_ADM.ALTER_OUTBOUND(
server_name    => 'xout',
table_names    => 'oe.orders, oe.order_items',
schema_names   => 'hr',
add            => FALSE,
inclusion_rule => TRUE);
END;
/

Example 5-20 Removing Rules for the hr Schema from the Negative Rule Set

BEGIN
DBMS_XSTREAM_ADM.ALTER_OUTBOUND(
server_name    => 'xout',
table_names    => NULL,
schema_names   => 'hr',
add            => FALSE,
inclusion_rule => FALSE);
END;
/

See Also:

- Oracle Database PL/SQL Packages and Types Reference

- "Declarative Rule-Based Transformations"

Removing Subset Rules from an Outbound Server's Positive Rule Set

This section describes removing subset rules from an outbound server's positive rule set using the REMOVE_SUBSET_OUTBOUND_RULES procedure in the DBMS_XSTREAM_ADM package. The REMOVE_SUBSET_OUTBOUND_RULES procedure only removes rules for DML changes. It does not remove rules for DDL changes, and it does not remove rules from a capture process's rule set.

To remove subset rules from an outbound server's positive rule set:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Determine the rule names for the subset rules by running the following query:

SELECT RULE_OWNER, SUBSETTING_OPERATION, RULE_NAME
FROM ALL_XSTREAM_RULES
WHERE SUBSETTING_OPERATION IS NOT NULL;

3. Run the REMOVE_SUBSET_OUTBOUND_RULES procedure, and specify the rules to remove from the list of rules displayed in Step 2.
For example, assume that Step 2 returned the following results:

RULE_OWNER                     SUBSET RULE_NAME
------------------------------ ------ ------------------------------
XSTRMADMIN                     INSERT EMPLOYEES71
XSTRMADMIN                     UPDATE EMPLOYEES72
XSTRMADMIN                     DELETE EMPLOYEES73

Example 5-21 Removing Subset Rules From an Outbound Server's Positive Rule Set

To remove these rules from the positive rule set of the xout outbound server, run the following procedure:

BEGIN
DBMS_XSTREAM_ADM.REMOVE_SUBSET_OUTBOUND_RULES(
server_name      => 'xout',
insert_rule_name => 'xstrmadmin.employees71',
update_rule_name => 'xstrmadmin.employees72',
delete_rule_name => 'xstrmadmin.employees73');
END;
/

4. If subset rules should also be removed from the rule set of a capture process and propagation that streams row LCRs to the outbound server, then see "Removing Rules Using the REMOVE_RULE Procedure" for information about removing rules.

See Also:
Oracle Database PL/SQL Packages and Types Reference

Removing Rules Using the REMOVE_RULE Procedure

This section describes removing a single rule from an XStream Out component's rule set or all rules from the rule set using the REMOVE_RULE procedure in the DBMS_XSTREAM_ADM package. The XStream Out component can be a capture process, propagation, or outbound server.

The REMOVE_RULE procedure only can remove rules for both DML and DDL changes, and it can remove rules from either the component's positive rule set or negative rule set.

To remove a single rule or all rules from an outbound server's rule set:

1. Connect to the database running the XStream Out component as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Determine the rule name and XStream component name.
See "Monitoring XStream Rules" for a query that displays this information.

3. Run the REMOVE_RULE procedure.

Example 5-22 Removing a Rule From an Outbound Server's Rule Set

This example removes a rule named orders12 from positive rule set of the xout outbound server.

BEGIN
DBMS_XSTREAM_ADM.REMOVE_RULE(
rule_name      => 'orders12',
streams_type   => 'APPLY',
streams_name   => 'xout',
inclusion_rule => TRUE);
/

The inclusion_rule parameter is set to TRUE to indicate the positive rule set.

Example 5-23 Removing All of the Rules From an Outbound Server's Rule Set

This example removes all of the rules from the negative rule set of the xout outbound server.

BEGIN
DBMS_XSTREAM_ADM.REMOVE_RULE(
rule_name      => NULL,
streams_type   => 'APPLY',
streams_name   => 'xout',
inclusion_rule => FALSE);
/

The rule_name parameter is set to NULL to specify that all of the rules are removed from the rule set, and the inclusion_rule parameter is set to FALSE to indicate the negative rule set.

See Also:
Oracle Database PL/SQL Packages and Types Reference

Managing Declarative Rule-Based Transformations

Declarative rule-based transformations cover a set of common transformation scenarios for row LCRs. You can use the following procedures in the DBMS_XSTREAM_ADM package to manage declarative rule-based transformations: ADD_COLUMN, DELETE_COLUMN, KEEP_COLUMNS, RENAME_COLUMN, RENAME_SCHEMA, and RENAME_TABLE.

This section contains the following topics:

- Adding Declarative Rule-Based Transformations

- Overwriting Existing Declarative Rule-Based Transformations

- Removing Declarative Rule-Based Transformations

See Also:
"Declarative Rule-Based Transformations"

Adding Declarative Rule-Based Transformations

The following sections contain examples that add declarative rule-based transformations to DML rules:

- Adding a Declarative Rule-Based Transformation That Renames a Table

- Adding a Declarative Rule-Based Transformation That Adds a Column

Note:
Declarative rule-based transformations can be specified for DML rules only. They cannot be specified for DDL rules.

Adding a Declarative Rule-Based Transformation That Renames a Table

Use the RENAME_TABLE procedure in the DBMS_XSTREAM_ADM package to add a declarative rule-based transformation that renames a table in a row LCR. The example in this section adds a declarative rule-based transformation to the jobs12 rule in the xstrmadmin schema.

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following procedure:

BEGIN
DBMS_XSTREAM_ADM.RENAME_TABLE(
rule_name       => 'xstrmadmin.jobs12',
from_table_name => 'hr.jobs',
to_table_name   => 'hr.assignments',
step_number     => 0,
operation       => 'ADD');
END;
/

The declarative rule-based transformation added by this procedure renames the table hr.jobs to hr.assignments in a row LCR when the rule jobs12 evaluates to TRUE for the row LCR. If more than one declarative rule-based transformation is specified for the jobs12 rule, then this transformation follows default transformation ordering because the step_number parameter is set to 0 (zero). In addition, the operation parameter is set to ADD to indicate that the transformation is being added to the rule, not removed from it.

The RENAME_TABLE procedure can also add a transformation that renames the schema in addition to the table. For example, in the previous example, to specify that the schema should be renamed to oe, specify oe.assignments for the to_table_name parameter.

Adding a Declarative Rule-Based Transformation That Adds a Column

Use the ADD_COLUMN procedure in the DBMS_XSTREAM_ADM package to add a declarative rule-based transformation that adds a column to a row in a row LCR. The example in this section adds a declarative rule-based transformation to the employees35 rule in the xstrmadmin schema.

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following procedure:

BEGIN
DBMS_XSTREAM_ADM.ADD_COLUMN(
rule_name    => 'xstrmadmin.employees35',
table_name   => 'hr.employees',
column_name  => 'birth_date',
column_value => ANYDATA.ConvertDate(NULL),
value_type   => 'NEW',
step_number  => 0,
operation    => 'ADD');
END;
/

The declarative rule-based transformation added by this procedure adds a birth_date column of data type DATE to an hr.employees table row in a row LCR when the rule employees35 evaluates to TRUE for the row LCR.

Notice that the ANYDATA.ConvertDate function specifies the column type and the column value. In this example, the added column value is NULL, but a valid date can also be specified. Use the appropriate ANYDATA function for the column being added. For example, if the data type of the column being added is NUMBER, then use the ANYDATA.ConvertNumber function.

The value_type parameter is set to NEW to indicate that the column is added to the new values in a row LCR. You can also specify OLD to add the column to the old values.

If more than one declarative rule-based transformation is specified for the employees35 rule, then the transformation follows default transformation ordering because the step_number parameter is set to 0 (zero). In addition, the operation parameter is set to ADD to indicate that the transformation is being added, not removed.

Note:
The ADD_COLUMN procedure is overloaded. A column_function parameter can specify that the current system date or time stamp is the value for the added column. The column_value and column_function parameters are mutually exclusive.

See Also:
Oracle Database PL/SQL Packages and Types Reference for more information about AnyData type functions

Overwriting Existing Declarative Rule-Based Transformations

When the operation parameter is set to ADD in a procedure that adds a declarative rule-based transformation, an existing declarative rule-based transformation is overwritten if the parameters in the following list match the existing transformation parameters:

- ADD_COLUMN procedure: rule_name, table_name, column_name, and step_number parameters

- DELETE_COLUMN procedure: rule_name, table_name, column_name, and step_number parameters

- KEEP_COLUMNS procedure: rule_name, table_name, column_list, and step_number parameters, or rule_name, table_name, column_table, and step_number parameters (The column_list and column_table parameters are mutually exclusive.)

- RENAME_COLUMN procedure: rule_name, table_name, from_column_name, and step_number parameters

- RENAME_SCHEMA procedure: rule_name, from_schema_name, and step_number parameters

- RENAME_TABLE procedure: rule_name, from_table_name, and step_number parameters

To overwrite an existing rule-based transformation:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the appropriate procedure in the DBMS_XSTREAM_ADM package, and specify the appropriate parameters.

Example 5-24 Overwriting a RENAME_COLUMN Declarative Rule-Based Transformation

Suppose an existing declarative rule-based transformation was creating by running the following procedure:

BEGIN
DBMS_XSTREAM_ADM.RENAME_COLUMN(
rule_name         => 'departments33',
table_name        => 'hr.departments',
from_column_name  => 'manager_id',
to_column_name    => 'lead_id',
value_type        => 'NEW',
step_number       => 0,
operation         => 'ADD');
END;
/

Running the following procedure overwrites this existing declarative rule-based transformation:

BEGIN
DBMS_XSTREAM_ADM.RENAME_COLUMN(
rule_name         => 'departments33',
table_name        => 'hr.departments',
from_column_name  => 'manager_id',
to_column_name    => 'lead_id',
value_type        => '*',
step_number       => 0,
operation         => 'ADD');
END;
/

In this case, the value_type parameter in the declarative rule-based transformation was changed from NEW to *. That is, in the original transformation, only new values were renamed in row LCRs, but, in the new transformation, both old and new values are renamed in row LCRs.

Removing Declarative Rule-Based Transformations

To remove a declarative rule-based transformation from a rule, use the same procedure used to add the transformation, but specify REMOVE for the operation parameter.

To remove a declarative rule-based transformation:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the appropriate procedure in the DBMS_XSTREAM_ADM package and specify REMOVE for the operation parameter.

Example 5-25 Removing a RENAME_TABLE Declarative Rule-Based Transformation

To remove the transformation added in "Adding a Declarative Rule-Based Transformation That Renames a Table", run the following procedure:

BEGIN
DBMS_XSTREAM_ADM.RENAME_TABLE(
rule_name       => 'strmadmin.jobs12',
from_table_name => 'hr.jobs',
to_table_name   => 'hr.assignments',
step_number     => 0,
operation       => 'REMOVE');
END;
/

When the operation parameter is set to REMOVE in any of the declarative transformation procedures listed in "Managing Declarative Rule-Based Transformations", the other parameters in the procedure are optional, excluding the rule_name parameter. If these optional parameters are set to NULL, then they become wildcards.

The RENAME_TABLE procedure in the previous example behaves in the following way when one or more of the optional parameters are set to NULL:

from_table_name Parameter

to_table_name Parameter

step_number Parameter

Result

NULL

NULL

NULL

Remove all rename table transformations for the specified rule

non-NULL

NULL

NULL

Remove all rename table transformations with the specified from_table_name for the specified rule

NULL

non-NULL

NULL

Remove all rename table transformations with the specified to_table_name for the specified rule

NULL

NULL

non-NULL

Remove all rename table transformations with the specified step_number for the specified rule

non-NULL

non-NULL

NULL

Remove all rename table transformations with the specified from_table_name and to_table_name for the specified rule

NULL

non-NULL

non-NULL

Remove all rename table transformations with the specified to_table_name and step_number for the specified rule

non-NULL

NULL

non-NULL

Remove all rename table transformations with the specified from_table_name and step_number for the specified rule

The other declarative transformation procedures work in a similar way when optional parameters are set to NULL and the operation parameter is set to REMOVE.

Dropping Components in an XStream Out Configuration

This section describes dropping an outbound server using the DROP_OUTBOUND procedure in the DBMS_XSTREAM_ADM package.

This procedure always drops the specified outbound server. This procedure also drops the queue used by the outbound server if both of the following conditions are met:

- The queue was created by the ADD_OUTBOUND or CREATE_OUTBOUND procedure in the DBMS_XSTREAM_ADM package.

- The outbound server is the only subscriber to the queue.

If either one of the preceding conditions is not met, then the DROP_OUTBOUND procedure only drops the outbound server. It does not drop the queue.

This procedure also drops the capture process for the outbound server if both of the following conditions are met:

- The procedure can drop the outbound server's queue.

- The DBMS_XSTREAM_ADM package can manage the outbound server's capture process. See "Checking Whether the DBMS_XSTREAM_ADM Package Can Manage a Capture Process".

If the procedure can drop the queue but cannot manage the capture process, then it drops the queue without dropping the capture process.

To drop an outbound server:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the DROP_OUTBOUND procedure.

Example 5-26 Dropping an Outbound Server

To drop an outbound server named xout, run the following procedure:

exec DBMS_XSTREAM_ADM.DROP_OUTBOUND('xout');

See Also:

- Oracle Database PL/SQL Packages and Types Reference for information about the DROP_OUTBOUND procedure

- Oracle Streams Concepts and Administration for information about dropping a queue or a capture process

Removing an XStream Out Configuration

You run the REMOVE_XSTREAM_CONFIGURATION procedure in the DBMS_XSTREAM_ADM package to remove an XStream Out configuration in a multitenant container database (CDB) or non-CDB.

Caution:
Running this procedure is dangerous. You should run this procedure only if you are sure you want to remove the entire XStream Out configuration at a database. This procedure also removes all XStream In components, Oracle GoldenGate components, and Oracle Streams components from the database.

To remove the XStream Out configuration:

1. Connect to the outbound server database as the XStream administrator.
In a CDB, connect to the root.

See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the REMOVE_XSTREAM_CONFIGURATION procedure.
In a non-CDB, run the following procedure:

EXEC DBMS_XSTREAM_ADM.REMOVE_XSTREAM_CONFIGURATION();

In a CDB, ensure that all containers are open in read/write mode and run the following procedure:

EXEC DBMS_XSTREAM_ADM.REMOVE_XSTREAM_CONFIGURATION(container => 'ALL');

Setting the container parameter to ALL removes the XStream configuration from all containers in the CDB.

After running this procedure, drop the XStream administrator at the database, if possible.

See Also:
Oracle Database PL/SQL Packages and Types Reference for detailed information about the actions performed by the REMOVE_XSTREAM_CONFIGURATION procedure

6 Monitoring XStream Out

This chapter provides instructions for monitoring XStream.

This chapter contains these topics:

- About Monitoring XStream Out

- Monitoring Session Information About XStream Out Components

- Monitoring XStream Out

- Monitoring the Capture Process for an Outbound Server

- Monitoring XStream Rules

- Monitoring Declarative Rule-Based Transformations

Note:
Whenever possible, this chapter uses ALL_ static data dictionary views for query examples. In some cases, information in the ALL_ views is more limited than the information in the DBA_ views.

See Also:

- Chapter 3, "XStream Out Concepts"

- "XStream Use Cases"

- Chapter 4, "Configuring XStream Out"

- Chapter 7, "Troubleshooting XStream Out"

About Monitoring XStream Out

This chapter describes monitoring an XStream Out configuration and an XStream In configuration. This chapter provides instructions for querying data dictionary views related to XStream. The queries provide information about XStream components and statistics related to XStream.

The main interface for monitoring XStream database components is SQL*Plus, although you can monitor some aspects of an XStream configuring using Oracle Enterprise Manager Cloud Control. For example, you can view information about capture processes, outbound servers, inbound servers, and rules in Oracle Enterprise Manager Cloud Control.

In SQL*Plus, trusted XStream administrators can query the ALL_ and DBA_ views. Untrusted XStream administrators can query the ALL_ views only.

This chapter also describes using the Oracle Streams Performance Advisor to monitor an XStream configuration. The Oracle Streams Performance Advisor consists of the DBMS_STREAMS_ADVISOR_ADM package and a collection of data dictionary views. The Oracle Streams Performance Advisor enables you to monitor the topology and performance of an XStream environment.

Monitoring Session Information About XStream Out Components

The query in this section displays the following session information about each XStream component in a database:

- The XStream component name

- The session identifier

- The serial number

- The operating system process identification number

- The XStream program name

This query is especially useful for determining the session information for specific XStream components when there are multiple XStream Out components configured in a database.

To display this information for each XStream component in a database:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN ACTION HEADING 'XStream Component' FORMAT A30
COLUMN SID HEADING 'Session ID' FORMAT 99999
COLUMN SERIAL# HEADING 'Session|Serial|Number' FORMAT 99999999
COLUMN PROCESS HEADING 'Operating System|Process ID' FORMAT A17
COLUMN PROCESS_NAME HEADING 'XStream|Program|Name' FORMAT A7

SELECT /*+PARAM('_module_action_old_length',0)*/ ACTION,
SID,
SERIAL#,
PROCESS,
SUBSTR(PROGRAM,INSTR(PROGRAM,'(')+1,4) PROCESS_NAME
FROM V$SESSION
WHERE MODULE ='XStream';

Your output for an XStream Out configuration looks similar to the following:

Session                   XStream
Serial Operating System  Program
XStream Component              Session ID    Number Process ID        Name
------------------------------ ---------- --------- ----------------- -------
XOUT - Apply Coordinator               21         9 27222             AP01
CAP$_XOUT_18 - Capture                 28        33 27248             CP01
XOUT - Apply Server                    97        43 27226             AS00
XOUT - Apply Reader                   105         5 27224             AS01
XOUT - Apply Server                   112        27 27342             TNS
XOUT - Propagation Send/Rcv           117         5 27250             CS00

The row that shows TNS for the XStream program name contains information about the session for the XStream client application that is attached to the outbound server.

See Also:
Oracle Database Reference for more information about the V$SESSION view

Monitoring XStream Out

This section provides sample queries that you can use to monitor XStream Out.

This section contains these topics:

- Displaying General Information About an Outbound Server

- Displaying Status and Error Information for an Outbound Server

- Displaying Information About an Outbound Server's Current Transaction

- Displaying Statistics for an Outbound Server

- Displaying the Processed Low Position for an Outbound Server

- Determining the Process Information for an Outbound Server

- Displaying the Apply Parameter Settings for an Outbound Server

With XStream Out, an Oracle Streams apply process functions as an outbound server. Therefore, you can also use the data dictionary views for apply processes to monitor outbound servers. In addition, an XStream Out environment includes capture processes and queues, and might include other components, such as propagations, rules, and rule-based transformations.

See Also:
Oracle Streams Concepts and Administration

Displaying General Information About an Outbound Server

You can display the following information for an outbound server by running the query in this section:

- The outbound server name

- The name of the connect user for the outbound server
The connect user is the user who can attach to the outbound server to retrieve the logical change record (LCR) stream. The client application must attach to the outbound server as the specified connect user.

- The name of the capture user for the capture process that captures changes for the outbound server to process

- The name of the capture process that captures changes for the outbound server to process

- The name of the source database for the captured changes

- The owner of the queue used by the outbound server

- The name of the queue used by the outbound server

The ALL_XSTREAM_OUTBOUND view contains information about the capture user, the capture process, and the source database in either of the following cases:

- The outbound server was created using the CREATE_OUTBOUND procedure in the DBMS_XSTREAM_ADM package.

- The outbound server was created using the ADD_OUTBOUND procedure in the DBMS_XSTREAM_ADM package, and the capture process for the outbound server runs on the same database as the outbound server.

If the outbound server was created using the ADD_OUTBOUND procedure, and the capture process for the outbound server is on a different database, then the ALL_XSTREAM_OUTBOUND view does not contain information about the capture user, the capture process, or the source database.

To display this general information about an outbound server:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN SERVER_NAME HEADING 'Outbound|Server|Name' FORMAT A10
COLUMN CONNECT_USER HEADING 'Connect|User' FORMAT A10
COLUMN CAPTURE_USER HEADING 'Capture|User' FORMAT A10
COLUMN CAPTURE_NAME HEADING 'Capture|Process|Name' FORMAT A12
COLUMN SOURCE_DATABASE HEADING 'Source|Database' FORMAT A11
COLUMN QUEUE_OWNER HEADING 'Queue|Owner' FORMAT A10
COLUMN QUEUE_NAME HEADING 'Queue|Name' FORMAT A10

SELECT SERVER_NAME,
CONNECT_USER,
CAPTURE_USER,
CAPTURE_NAME,
SOURCE_DATABASE,
QUEUE_OWNER,
QUEUE_NAME
FROM ALL_XSTREAM_OUTBOUND;

Your output looks similar to the following:

Outbound                         Capture
Server     Connect    Capture    Process      Source      Queue      Queue
Name       User       User       Name         Database    Owner      Name
---------- ---------- ---------- ------------ ----------- ---------- ----------
XOUT       XSTRMADMIN XSTRMADMIN CAP$_XOUT_18 XOUT.EXAMPL XSTRMADMIN Q$_XOUT_19
E.COM

See Also:
Oracle Database Reference

Displaying Status and Error Information for an Outbound Server

The DBA_APPLY view shows XStream Out in the PURPOSE column for an apply process that is functioning as an outbound server.

To display detailed information about an outbound server:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN APPLY_NAME HEADING 'Outbound Server|Name' FORMAT A15
COLUMN STATUS HEADING 'Status' FORMAT A8
COLUMN ERROR_NUMBER HEADING 'Error Number' FORMAT 9999999
COLUMN ERROR_MESSAGE HEADING 'Error Message' FORMAT A40

SELECT APPLY_NAME,
STATUS,
ERROR_NUMBER,
ERROR_MESSAGE
FROM DBA_APPLY
WHERE PURPOSE = 'XStream Out';

Your output looks similar to the following:

Outbound Server
Name            Status   Error Number Error Message
--------------- -------- ------------ ----------------------------------------
XOUT            ENABLED

This output shows that XOUT is an apply process that is functioning as an outbound server.

Note:
This example queries the DBA_APPLY view. This view enables trusted users to see information for all apply users in the database. Untrusted users must query the ALL_APPLY view, which limits information to the current user.

See Also:
Oracle Database Reference

Displaying Information About an Outbound Server's Current Transaction

The V$XSTREAM_OUTBOUND_SERVER view contains the following information about the transaction currently being processed by an XStream outbound server:

- The name of the outbound server

- The transaction ID of the transaction currently being processed

- Commit system change number (SCN) of the transaction currently being processed

- Commit position of the transaction currently being processed

- The position of the last LCR sent to the XStream client application

- The message number of the current LCR being processed by the outbound server

Run this query to determine how many LCRs an outbound server has processed in a specific transaction. You can query the TOTAL_MESSAGE_COUNT column in the V$XSTREAM_TRANSACTION view to determine the total number of LCRs in a transaction.

To display information about an outbound server's current transaction:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN SERVER_NAME HEADING 'Outbound|Server|Name' FORMAT A10
COLUMN 'Transaction ID' HEADING 'Transaction|ID' FORMAT A11
COLUMN COMMITSCN HEADING 'Commit SCN' FORMAT 9999999999999
COLUMN COMMIT_POSITION HEADING 'Commit Position' FORMAT A15
COLUMN LAST_SENT_POSITION HEADING 'Last Sent|Position' FORMAT A15
COLUMN MESSAGE_SEQUENCE HEADING 'Message|Number' FORMAT 999999999

SELECT SERVER_NAME,
XIDUSN ||'.'||
XIDSLT ||'.'||
XIDSQN "Transaction ID",
COMMITSCN,
COMMIT_POSITION,
LAST_SENT_POSITION,
MESSAGE_SEQUENCE
FROM V$XSTREAM_OUTBOUND_SERVER;

Your output looks similar to the following:

Outbound
Server     Transaction                                Last Sent          Message
Name       ID              Commit SCN Commit Position Position            Number
---------- ----------- -------------- --------------- --------------- ----------
XOUT       2.22.304            820023 0000000C82E4000 0000000C8337000        616
000010000000100 000010000000100
00000C82E400000 00000C833700000
0010000000101   0010000000101

Note:
The COMMITSCN and COMMIT_POSITION values are populated only if the COMMITTED_DATA_ONLY value is YES in V$XSTREAM_OUTBOUND_SERVER.

See Also:
Oracle Database Reference

Displaying Statistics for an Outbound Server

The V$XSTREAM_OUTBOUND_SERVER view contains the following statistics about the database changes processed by an XStream outbound server:

- The name of the outbound server

- The number of transactions sent from the outbound server to the XStream client application since the last time the client application attached to the outbound server

- The number of LCRs sent from the outbound server to the XStream client application since the last time the client application attached to the outbound server

- The number of megabytes sent from the outbound server to the XStream client application since the last time the client application attached to the outbound server

- The amount of time the outbound server spent sending LCRs to the XStream client application since the last time the client application attached to the outbound server

- The message number of the last LCR sent by the outbound server to the XStream client application

- Creation time at the source database of the last LCR sent by the outbound server to the client application

To display statistics for an outbound server:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN SERVER_NAME HEADING 'Outbound|Server|Name' FORMAT A8
COLUMN TOTAL_TRANSACTIONS_SENT HEADING 'Total|Trans|Sent' FORMAT 9999999
COLUMN TOTAL_MESSAGES_SENT HEADING 'Total|LCRs|Sent' FORMAT 9999999999
COLUMN BYTES_SENT HEADING 'Total|MB|Sent' FORMAT 99999999999999
COLUMN ELAPSED_SEND_TIME HEADING 'Time|Sending|LCRs|(in seconds)' FORMAT 99999999
COLUMN LAST_SENT_MESSAGE_NUMBER HEADING 'Last|Sent|Message|Number' FORMAT 99999999
COLUMN LAST_SENT_MESSAGE_CREATE_TIME HEADING 'Last|Sent|Message|Creation|Time' FORMAT A9

SELECT SERVER_NAME,
TOTAL_TRANSACTIONS_SENT,
TOTAL_MESSAGES_SENT,
(BYTES_SENT/1024)/1024 BYTES_SENT,
(ELAPSED_SEND_TIME/100) ELAPSED_SEND_TIME,
LAST_SENT_MESSAGE_NUMBER,
TO_CHAR(LAST_SENT_MESSAGE_CREATE_TIME,'HH24:MI:SS MM/DD/YY')
LAST_SENT_MESSAGE_CREATE_TIME
FROM V$XSTREAM_OUTBOUND_SERVER;

Your output looks similar to the following:

Last
Time      Last Sent
Outbound    Total       Total           Total      Sending      Sent Message
Server      Trans        LCRs              MB         LCRs   Message Creation
Name         Sent        Sent            Sent (in seconds)    Number Time
-------- -------- ----------- --------------- ------------ --------- ---------
XOUT         4028      256632              67            1    820023 10:11:00
02/28/11

Note:
The TOTAL_TRANSACTIONS_SENT value is populated only if the COMMITTED_DATA_ONLY value is YES in V$XSTREAM_OUTBOUND_SERVER.

See Also:
Oracle Database Reference

Displaying the Processed Low Position for an Outbound Server

For an outbound server, the processed low position is the position below which all transactions have been committed and logged by the client application. The processed low position is important when the outbound server or the client application is restarted.

You can display the following information about the processed low position for an outbound server by running the query in this section:

- The outbound server name

- The name of the source database for the captured changes

- The processed low position, which indicates the low watermark position processed by the client application

- The time when the processed low position was last updated by the outbound server

To display the processed low position for an outbound server:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN SERVER_NAME HEADING 'Outbound|Server|Name' FORMAT A10
COLUMN SOURCE_DATABASE HEADING 'Source|Database' FORMAT A20
COLUMN PROCESSED_LOW_POSITION HEADING 'Processed|Low LCR|Position' FORMAT A30
COLUMN PROCESSED_LOW_TIME HEADING 'Processed|Low|Time' FORMAT A9

SELECT SERVER_NAME,
SOURCE_DATABASE,
PROCESSED_LOW_POSITION,
TO_CHAR(PROCESSED_LOW_TIME,'HH24:MI:SS MM/DD/YY') PROCESSED_LOW_TIME
FROM ALL_XSTREAM_OUTBOUND_PROGRESS;

Your output looks similar to the following:

Outbound                        Processed                      Processed
Server     Source               Low LCR                        Low
Name       Database             Position                       Time
---------- -------------------- ------------------------------ ---------
XOUT       XOUT.EXAMPLE.COM     0000000C84EA000000000000000000 10:18:37
00000C84EA000000000000000001   02/28/11

See Also:

- Oracle Database Reference

- "The Processed Low Position and Restartability for XStream Out"

Determining the Process Information for an Outbound Server

An outbound server is an Oracle background process. This background process runs only when an XStream client application attaches to the outbound server. The V$XSTREAM_OUTBOUND_SERVER view contains information about this background process.

You can display the following information for an outbound server by running the query in this section:

- The outbound server name

- The session ID of the outbound server's session

- The serial number of the outbound server's session

- The process identification number of the operating-system process that sends LCRs to the client application

To display the process information for an outbound server:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN SERVER_NAME HEADING 'Outbound Server Name' FORMAT A20
COLUMN SID HEADING 'Session ID' FORMAT 9999999999
COLUMN SERIAL# HEADING 'Serial Number' FORMAT 9999999999
COLUMN SPID HEADING 'Operating-System Process' FORMAT A25

SELECT SERVER_NAME,
SID,
SERIAL#,
SPID
FROM V$XSTREAM_OUTBOUND_SERVER;

Your output looks similar to the following:

Outbound Server Name  Session ID Serial Number Operating-System Process
-------------------- ----------- ------------- -------------------------
XOUT                          18            19 15906

Note:
The V$XSTREAM_APPLY_SERVER view provides additional information about the outbound server process, and information about the apply server background processes used by the outbound server.

See Also:
Oracle Database Reference

Displaying the Apply Parameter Settings for an Outbound Server

Apply parameters determine how an outbound server operates.

To display the apply parameter settings for an outbound server:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN APPLY_NAME HEADING 'Outbound Server|Name' FORMAT A15
COLUMN PARAMETER HEADING 'Parameter' FORMAT A30
COLUMN VALUE HEADING 'Value' FORMAT A22
COLUMN SET_BY_USER HEADING 'Set by|User?' FORMAT A10

SELECT APPLY_NAME,
PARAMETER,
VALUE,
SET_BY_USER
FROM ALL_APPLY_PARAMETERS a, ALL_XSTREAM_OUTBOUND o
WHERE a.APPLY_NAME=o.SERVER_NAME
ORDER BY a.PARAMETER;

Your output looks similar to the following:

Outbound Server                                                       Set by
Name            Parameter                      Value                  User?
--------------- ------------------------------ ---------------------- ----------
XOUT            ALLOW_DUPLICATE_ROWS           N                      NO
XOUT            APPLY_SEQUENCE_NEXTVAL         Y                      NO
XOUT            COMMIT_SERIALIZATION           DEPENDENT_TRANSACTIONS NO
XOUT            COMPARE_KEY_ONLY               N                      NO
XOUT            COMPUTE_LCR_DEP_ON_ARRIVAL     N                      NO
XOUT            DISABLE_ON_ERROR               Y                      NO
XOUT            DISABLE_ON_LIMIT               N                      NO
XOUT            EAGER_SIZE                     9500                   NO
XOUT            ENABLE_XSTREAM_TABLE_STATS     Y                      NO
XOUT            EXCLUDETAG                                            NO
XOUT            EXCLUDETRANS                                          NO
XOUT            EXCLUDEUSER                                           NO
XOUT            EXCLUDEUSERID                                         NO
XOUT            GETAPPLOPS                     Y                      NO
XOUT            GETREPLICATES                  N                      NO
XOUT            GROUPTRANSOPS                  10000                  NO
XOUT            HANDLECOLLISIONS               N                      NO
XOUT            IGNORE_TRANSACTION                                    NO
XOUT            MAXIMUM_SCN                    INFINITE               NO
XOUT            MAX_PARALLELISM                1                      NO
XOUT            MAX_SGA_SIZE                   INFINITE               NO
XOUT            OPTIMIZE_PROGRESS_TABLE        Y                      NO
XOUT            OPTIMIZE_SELF_UPDATES          Y                      NO
XOUT            PARALLELISM                    1                      NO
XOUT            PRESERVE_ENCRYPTION            Y                      NO
XOUT            RTRIM_ON_IMPLICIT_CONVERSION   Y                      NO
XOUT            STARTUP_SECONDS                0                      NO
XOUT            SUPPRESSTRIGGERS               Y                      NO
XOUT            TIME_LIMIT                     INFINITE               NO
XOUT            TRACE_LEVEL                    0                      NO
XOUT            TRANSACTION_LIMIT              INFINITE               NO
XOUT            TXN_AGE_SPILL_THRESHOLD        900                    NO
XOUT            TXN_LCR_SPILL_THRESHOLD        10000                  NO
XOUT            WRITE_ALERT_LOG                Y                      NO

Outbound servers ignore some apply parameter settings. See Oracle Database PL/SQL Packages and Types Reference for information about these apply parameters.

Note:
If the Set by User? column is NO for a parameter, then the parameter is set to its default value. If the Set by User? column is YES for a parameter, then the parameter was set by a user and might or might not be set to its default value.

See Also:

- "Setting an Apply Parameter for an Outbound Server"

- Oracle Database PL/SQL Packages and Types Reference for information about apply parameters

Monitoring the Capture Process for an Outbound Server

This section provides sample queries that you can use to monitor the capture process for an outbound server.

This section contains these topics:

- Displaying Change Capture Information About Each Capture Process

- Displaying the Registered Redo Log Files for Each Capture Process

- Displaying Redo Log Files That Are Required by Each Capture Process

- Displaying SCN Values for Each Redo Log File Used by Each Capture Process

- Listing the Parameter Settings for Each Capture Process

- Determining the Applied SCN for Each Capture Process

- Displaying the Redo Log Scanning Latency for Each Capture Process

- Displaying the Extra Attributes Captured by a Capture Process

See Also:
Oracle Streams Concepts and Administration includes more queries that you can use to monitor a capture process

Displaying Change Capture Information About Each Capture Process

The query in this section displays the following information about each capture process in a database:

- The name of the capture process.

- The current state of the capture process
See "Capture Process States".

- The total number of redo entries passed by LogMiner to the capture process for detailed rule evaluation. A capture process converts a redo entry into an LCR and performs detailed rule evaluation on the LCR when capture process prefiltering cannot discard the change.

- The total number LCRs enqueued since the capture process was last started.

To display this change capture information about each capture process in a database:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture|Name' FORMAT A15
COLUMN STATE HEADING 'State' FORMAT A25
COLUMN TOTAL_MESSAGES_CAPTURED HEADING 'Redo|Entries|Evaluated|In Detail' FORMAT 99999999999999
COLUMN TOTAL_MESSAGES_ENQUEUED HEADING 'Total|LCRs|Enqueued' FORMAT 99999999999999

SELECT CAPTURE_NAME,
STATE,
TOTAL_MESSAGES_CAPTURED,
TOTAL_MESSAGES_ENQUEUED
FROM V$XSTREAM_CAPTURE;

Your output looks similar to the following:

Redo
Entries           Total
Capture                                         Evaluated            LCRs
Name            State                           In Detail        Enqueued
--------------- ------------------------- --------------- ---------------
CAP$_XOUT_1     WAITING FOR TRANSACTION            297666          261798

The number of redo entries scanned can be higher than the number of DML and DDL redo entries captured by a capture process. Only DML and DDL redo entries that satisfy the rule sets of a capture process are captured and sent to an outbound server. Also, the total LCRs enqueued includes LCRs that contain transaction control statements. These row LCRs contain directives such as COMMIT and ROLLBACK. Therefore, the total LCRs enqueued is a number higher than the number of row changes and DDL changes enqueued by a capture process.

See Also:
"Row LCRs" for more information about transaction control statements

Displaying the Registered Redo Log Files for Each Capture Process

You can display information about the archived redo log files that are registered for each capture process in a database by running the query in this section. This query displays information about these files for both local capture processes and downstream capture processes.

The query displays the following information for each registered archived redo log file:

- The name of a capture process that uses the file

- The source database of the file

- The sequence number of the file

- The name and location of the file at the local site

- Whether the file contains the beginning of a data dictionary build

- Whether the file contains the end of a data dictionary build

To display the registered redo log files for each capture process:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN CONSUMER_NAME HEADING 'Capture|Process|Name' FORMAT A15
COLUMN SOURCE_DATABASE HEADING 'Source|Database' FORMAT A10
COLUMN SEQUENCE# HEADING 'Sequence|Number' FORMAT 99999
COLUMN NAME HEADING 'Archived Redo Log|File Name' FORMAT A20
COLUMN DICTIONARY_BEGIN HEADING 'Dictionary|Build|Begin' FORMAT A10
COLUMN DICTIONARY_END HEADING 'Dictionary|Build|End' FORMAT A10

SELECT r.CONSUMER_NAME,
r.SOURCE_DATABASE,
r.SEQUENCE#,
r.NAME,
r.DICTIONARY_BEGIN,
r.DICTIONARY_END
FROM DBA_REGISTERED_ARCHIVED_LOG r, ALL_CAPTURE c
WHERE r.CONSUMER_NAME = c.CAPTURE_NAME;

Your output looks similar to the following:

Capture                                                  Dictionary Dictionary
Process         Source     Sequence Archived Redo Log    Build      Build
Name            Database     Number File Name            Begin      End
--------------- ---------- -------- -------------------- ---------- ----------
CAP$_XOUT_1     DBS2.EXAMP       15 /orc/dbs/log/arch2_1 NO         NO
LE.COM              _15_478347508.arc
CAP$_XOUT_1     DBS2.EXAMP       16 /orc/dbs/log/arch2_1 NO         NO
LE.COM              _16_478347508.arc
CAP$_XOUT_2     DBS1.EXAMP       45 /remote_logs/arch1_1 YES        YES
LE.COM              _45_478347335.arc
CAP$_XOUT_2     DBS1.EXAMP       46 /remote_logs/arch1_1 NO         NO
LE.COM              _46_478347335.arc
CAP$_XOUT_2     DBS1.EXAMP       47 /remote_logs/arch1_1 NO         NO
LE.COM              _47_478347335.arc

Assume that this query was run at the dbs2.example.com database, and that cap$_xout_1 is a local capture process, and cap$_xout_2 is a downstream capture process. The source database for the cap$_xout_2 downstream capture process is dbs1.example.com. This query shows that there are two registered archived redo log files for cap$_xout_1 and three registered archived redo log files for cap$_xout_2. This query shows the name and location of each of these files in the local file system.

See Also:

- "Capture Process Overview"

- "Local Capture and Downstream Capture"

- "SCN Values Related to a Capture Process" for information about dictionary builds

Displaying Redo Log Files That Are Required by Each Capture Process

A capture process needs the redo log file that includes the required checkpoint SCN, and all subsequent redo log files. You can query the REQUIRED_CHECKPOINT_SCN column in the ALL_CAPTURE data dictionary view to determine the required checkpoint SCN for a capture process. Redo log files before the redo log file that contains the required checkpoint SCN are no longer needed by the capture process. These redo log files can be stored offline if they are no longer needed for any other purpose. If you reset the start SCN for a capture process to a lower value in the future, then these redo log files might be needed.

The query displays the following information for each required archived redo log file:

- The name of a capture process that uses the file

- The source database of the file

- The sequence number of the file

- The name and location of the required redo log file at the local site

To display this information about each required archive redo log file in a database, run the following query:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN CONSUMER_NAME HEADING 'Capture|Process|Name' FORMAT A15
COLUMN SOURCE_DATABASE HEADING 'Source|Database' FORMAT A10
COLUMN SEQUENCE# HEADING 'Sequence|Number' FORMAT 99999
COLUMN NAME HEADING 'Required|Archived Redo Log|File Name' FORMAT A40

SELECT r.CONSUMER_NAME,
r.SOURCE_DATABASE,
r.SEQUENCE#,
r.NAME
FROM DBA_REGISTERED_ARCHIVED_LOG r, ALL_CAPTURE c
WHERE r.CONSUMER_NAME =  c.CAPTURE_NAME AND
r.NEXT_SCN      >= c.REQUIRED_CHECKPOINT_SCN;

Your output looks similar to the following:

Capture                             Required
Process         Source     Sequence Archived Redo Log
Name            Database     Number File Name
--------------- ---------- -------- ----------------------------------------
CAP$_XOUT_1     DBS2.EXAMP       16 /orc/dbs/log/arch2_1_16_478347508.arc
LE.COM
CAP$_XOUT_2     DBS1.EXAMP       47 /remote_logs/arch1_1_47_478347335.arc
LE.COM

See Also:
"Capture Process Overview"

Displaying SCN Values for Each Redo Log File Used by Each Capture Process

You can display information about the SCN values for archived redo log files that are registered for each capture process in a database by running the query in this section. This query displays information the SCN values for these files for both local capture processes and downstream capture processes. This query also identifies redo log files that are no longer needed by any capture process at the local database.

The query displays the following information for each registered archived redo log file:

- The capture process name of a capture process that uses the file

- The name and location of the file at the local site

- The lowest SCN value for the information contained in the redo log file

- The lowest SCN value for the next redo log file in the sequence

- Whether the redo log file is purgeable

To display SCN values for each redo log file used by each capture process:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN CONSUMER_NAME HEADING 'Capture|Process|Name' FORMAT A15
COLUMN NAME HEADING 'Archived Redo Log|File Name' FORMAT A25
COLUMN FIRST_SCN HEADING 'First SCN' FORMAT 99999999999
COLUMN NEXT_SCN HEADING 'Next SCN' FORMAT 99999999999
COLUMN PURGEABLE HEADING 'Purgeable?' FORMAT A10

SELECT r.CONSUMER_NAME,
r.NAME,
r.FIRST_SCN,
r.NEXT_SCN,
r.PURGEABLE
FROM DBA_REGISTERED_ARCHIVED_LOG r, ALL_CAPTURE c
WHERE r.CONSUMER_NAME = c.CAPTURE_NAME;

Your output looks similar to the following:

Capture
Process         Archived Redo Log
Name            File Name                    First SCN     Next SCN Purgeable?
--------------- ------------------------- ------------ ------------ ----------
CAP$_XOUT_1     /private1/ARCHIVE_LOGS/1_       509686       549100 YES
3_502628294.dbf

CAP$_XOUT_1     /private1/ARCHIVE_LOGS/1_       549100       587296 YES
4_502628294.dbf

CAP$_XOUT_1     /private1/ARCHIVE_LOGS/1_       587296       623107 NO
5_502628294.dbf

The redo log files with YES for Purgeable? for all capture processes will never be needed by any capture process at the local database. These redo log files can be removed without affecting any existing capture process at the local database. The redo log files with NO for Purgeable? for one or more capture processes must be retained.

Listing the Parameter Settings for Each Capture Process

Capture process parameters determine how a capture process operates.

To list the parameter settings for each capture process:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture|Process|Name' FORMAT A25
COLUMN PARAMETER HEADING 'Parameter' FORMAT A30
COLUMN VALUE HEADING 'Value' FORMAT A10
COLUMN SET_BY_USER HEADING 'Set by|User?' FORMAT A10

SELECT c.CAPTURE_NAME,
PARAMETER,
VALUE,
SET_BY_USER
FROM ALL_CAPTURE_PARAMETERS c, ALL_XSTREAM_OUTBOUND o
WHERE c.CAPTURE_NAME=o.CAPTURE_NAME
ORDER BY PARAMETER;

Your output looks similar to the following:

Capture
Process                                                             Set by
Name                      Parameter                      Value      User?
------------------------- ------------------------------ ---------- ----------
CAP$_XOUT_1               CAPTURE_IDKEY_OBJECTS          N          NO
CAP$_XOUT_1               CAPTURE_SEQUENCE_NEXTVAL       N          NO
CAP$_XOUT_1               DISABLE_ON_LIMIT               N          NO
CAP$_XOUT_1               DOWNSTREAM_REAL_TIME_MINE      Y          NO
CAP$_XOUT_1               EXCLUDETAG                                NO
CAP$_XOUT_1               EXCLUDETRANS                              NO
CAP$_XOUT_1               EXCLUDEUSER                               NO
CAP$_XOUT_1               EXCLUDEUSERID                             NO
CAP$_XOUT_1               GETAPPLOPS                     Y          NO
CAP$_XOUT_1               GETREPLICATES                  N          NO
CAP$_XOUT_1               IGNORE_TRANSACTION                        NO
CAP$_XOUT_1               IGNORE_UNSUPPORTED_TABLE       *          NO
CAP$_XOUT_1               INCLUDE_OBJECTS                           NO
CAP$_XOUT_1               INLINE_LOB_OPTIMIZATION        N          NO
CAP$_XOUT_1               MAXIMUM_SCN                    INFINITE   NO
CAP$_XOUT_1               MAX_SGA_SIZE                   INFINITE   NO
CAP$_XOUT_1               MERGE_THRESHOLD                60         NO
CAP$_XOUT_1               MESSAGE_LIMIT                  INFINITE   NO
CAP$_XOUT_1               MESSAGE_TRACKING_FREQUENCY     2000000    NO
CAP$_XOUT_1               PARALLELISM                    0          NO
CAP$_XOUT_1               SKIP_AUTOFILTERED_TABLE_DDL    Y          NO
CAP$_XOUT_1               SPLIT_THRESHOLD                1800       NO
CAP$_XOUT_1               STARTUP_SECONDS                0          NO
CAP$_XOUT_1               TIME_LIMIT                     INFINITE   NO
CAP$_XOUT_1               TRACE_LEVEL                    0          NO
CAP$_XOUT_1               USE_RAC_SERVICE                N          NO
CAP$_XOUT_1               WRITE_ALERT_LOG                Y          NO
CAP$_XOUT_1               XOUT_CLIENT_EXISTS             Y          NO

Note:
If the Set by User? column is NO for a parameter, then the parameter is set to its default value. If the Set by User? column is YES for a parameter, then the parameter was set by a user and might or might not be set to its default value.

See Also:

- "Capture Process Subcomponents"

- "Setting a Capture Process Parameter"

- Oracle Database PL/SQL Packages and Types Reference for information about capture process parameters

Determining the Applied SCN for Each Capture Process

The applied system change number (SCN) for a capture process is the SCN of the most recent logical change record (LCR) dequeued by the relevant outbound servers. All changes below this applied SCN have been processed by all outbound servers that process changes captured by the capture process.

To determine the applied SCN for each capture process:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture Process Name' FORMAT A30
COLUMN APPLIED_SCN HEADING 'Applied SCN' FORMAT 99999999999

SELECT CAPTURE_NAME, APPLIED_SCN FROM ALL_CAPTURE;

Your output looks similar to the following:

Capture Process Name            Applied SCN
------------------------------ ------------
CAP$_XOUT_1                          824825

Displaying the Redo Log Scanning Latency for Each Capture Process

You can find the following information about each capture process by running the query in this section:

- The redo log scanning latency, which specifies the number of seconds between the creation time of the most recent redo log entry scanned by a capture process and the current time. This number might be relatively large immediately after you start a capture process.

- The seconds since last recorded status, which is the number of seconds since a capture process last recorded its status.

- The current capture process time, which is the latest time when the capture process recorded its status.

- The logical change record (LCR) creation time, which is the time when the data manipulation language (DML) or data definition language (DDL) change generated the redo data at the source database for the most recently captured LCR.

The information displayed by this query is valid only for an enabled capture process.

To display the redo log scanning latency for each capture process:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture|Process|Name' FORMAT A12
COLUMN LATENCY_SECONDS HEADING 'Latency|in|Seconds' FORMAT 999999
COLUMN LAST_STATUS HEADING 'Seconds Since|Last Status' FORMAT 999999
COLUMN CAPTURE_TIME HEADING 'Current|Process|Time'
COLUMN CREATE_TIME HEADING 'Message|Creation Time' FORMAT 999999

SELECT CAPTURE_NAME,
((SYSDATE - CAPTURE_MESSAGE_CREATE_TIME)*86400) LATENCY_SECONDS,
((SYSDATE - CAPTURE_TIME)*86400) LAST_STATUS,
TO_CHAR(CAPTURE_TIME, 'HH24:MI:SS MM/DD/YY') CAPTURE_TIME,
TO_CHAR(CAPTURE_MESSAGE_CREATE_TIME, 'HH24:MI:SS MM/DD/YY') CREATE_TIME
FROM V$XSTREAM_CAPTURE;

Your output looks similar to the following:

Capture      Latency               Current
Process           in Seconds Since Process           Message
Name         Seconds   Last Status Time              Creation Time
------------ ------- ------------- ----------------- -----------------
CAP$_XOUT_1        1             1 10:32:52 02/28/11 10:32:52 02/28/11

The "Latency in Seconds" returned by this query is the difference between the current time (SYSDATE) and the "Message Creation Time." The "Seconds Since Last Status" returned by this query is the difference between the current time (SYSDATE) and the "Current Process Time."

Displaying the Extra Attributes Captured by a Capture Process

You can use the INCLUDE_EXTRA_ATTRIBUTE procedure in the DBMS_CAPTURE_ADM package to instruct a capture process to capture one or more extra attributes and include the extra attributes in logical change records (LCRs).

To display extra attributes captured by a capture process:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture Process' FORMAT A20
COLUMN ATTRIBUTE_NAME HEADING 'Attribute Name' FORMAT A15
COLUMN INCLUDE HEADING 'Include Attribute in LCRs?' FORMAT A30

SELECT CAPTURE_NAME, ATTRIBUTE_NAME, INCLUDE
FROM ALL_CAPTURE_EXTRA_ATTRIBUTES
ORDER BY CAPTURE_NAME;

Your output looks similar to the following:

Capture Process      Attribute Name  Include Attribute in LCRs?
-------------------- --------------- ------------------------------
CAP$_XOUT_1          ROW_ID          NO
CAP$_XOUT_1          SERIAL#         NO
CAP$_XOUT_1          SESSION#        NO
CAP$_XOUT_1          THREAD#         NO
CAP$_XOUT_1          TX_NAME         YES
CAP$_XOUT_1          USERNAME        NO

Based on this output, the capture process named xcapture includes the transaction name (tx_name) in the LCRs that it captures, but this capture process does not include any other extra attributes in the LCRs that it captures.

See Also:

- "Extra Information in Row LCRs and DDL LCRs"

- Oracle Database PL/SQL Packages and Types Reference for more information about the INCLUDE_EXTRA_ATTRIBUTE procedure

Monitoring XStream Rules

The ALL_XSTREAM_RULES view contains information about the rules used by outbound servers and inbound servers. If an outbound server was created using the CREATE_OUTBOUND procedure in the DBMS_XSTREAM_ADM package, then these views also contain information about the rules used by the capture process that sends changes to the outbound server. However, if an outbound server was created using the ADD_OUTBOUND procedure, then these views do not contain information about the capture process rules. Also, these views do not contain information about the rules used by any propagation in the stream from a capture process to an outbound server.

To display information about the rules used by XStream components:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN STREAMS_NAME HEADING 'XStream|Component|Name' FORMAT A9
COLUMN STREAMS_TYPE HEADING 'XStream|Component|Type' FORMAT A9
COLUMN RULE_NAME HEADING 'Rule|Name' FORMAT A13
COLUMN RULE_SET_TYPE HEADING 'Rule Set|Type' FORMAT A8
COLUMN STREAMS_RULE_TYPE HEADING 'Rule|Level' FORMAT A7
COLUMN SCHEMA_NAME HEADING 'Schema|Name' FORMAT A6
COLUMN OBJECT_NAME HEADING 'Object|Name' FORMAT A11
COLUMN RULE_TYPE HEADING 'Rule|Type' FORMAT A4

SELECT STREAMS_NAME,
STREAMS_TYPE,
RULE_NAME,
RULE_SET_TYPE,
STREAMS_RULE_TYPE,
SCHEMA_NAME,
OBJECT_NAME,
RULE_TYPE
FROM ALL_XSTREAM_RULES;

Your output looks similar to the following:

XStream   XStream
Component Component Rule          Rule Set Rule    Schema Object      Rule
Name      Type      Name          Type     Level   Name   Name        Type
--------- --------- ------------- -------- ------- ------ ----------- ----
XOUT      APPLY     ORDERS11      POSITIVE TABLE   OE     ORDERS      DML
XOUT      APPLY     ORDERS12      POSITIVE TABLE   OE     ORDERS      DDL
XOUT      APPLY     ORDER_ITEMS14 POSITIVE TABLE   OE     ORDER_ITEMS DML
XOUT      APPLY     ORDER_ITEMS15 POSITIVE TABLE   OE     ORDER_ITEMS DDL
XOUT      APPLY     HR16          POSITIVE SCHEMA  HR                 DML
XOUT      APPLY     HR17          POSITIVE SCHEMA  HR                 DDL

Notice that the STREAMS_TYPE is APPLY even though the rules are in the positive rule set for the outbound server xout. You can determine the purpose of an apply component by querying the PURPOSE column in the ALL_APPLY view.

The ALL_XSTREAM_RULES view contains more information about the rules used in an XStream configuration than what is shown in this example. For example, you can query this view to show information about the rule sets used by XStream components.

To view information about the rules used by all components, including capture processes, propagations, apply processes, outbound servers, and inbound servers, you can query the ALL_XSTREAM_RULES view. See Oracle Streams Concepts and Administration for sample queries that enable you to monitor rules.

See Also:
Oracle Database Reference

Monitoring Declarative Rule-Based Transformations

A declarative rule-based transformations is a rule-based transformation that covers one of a common set of transformation scenarios for row LCRs. Declarative rule-based transformations are run internally without using PL/SQL.

The query in this section displays the following information about each declarative rule-based transformation in a database:

- The owner of the rule for which a declarative rule-based transformation is specified.

- The name of the rule for which a declarative rule-based transformation is specified.

- The type of declarative rule-based transformation specified. The following types are possible: ADD COLUMN, DELETE COLUMN, KEEP COLUMNS, RENAME COLUMN, RENAME SCHEMA, and RENAME TABLE.

- The precedence of the declarative rule-based transformation. The precedence is the execution order of a transformation in relation to other transformations with the same step number specified for the same rule. For transformations with the same step number, the transformation with the lowest precedence is executed first.

- The step number of the declarative rule-based transformation. If more than one declarative rule-based transformation is specified for the same rule, then the transformation with the lowest step number is executed first. You can specify the step number for a declarative rule-based transformation when you create the transformation.

You must have DBA role in order to access the DBA_XSTREAM_TRANSFORMATIONS view.

Run the following query to display this information for the declarative rule-based transformations in a database:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN RULE_OWNER HEADING 'Rule Owner' FORMAT A15
COLUMN RULE_NAME HEADING 'Rule Name' FORMAT A15
COLUMN DECLARATIVE_TYPE HEADING 'Declarative|Type' FORMAT A15
COLUMN PRECEDENCE HEADING 'Precedence' FORMAT 99999
COLUMN STEP_NUMBER HEADING 'Step Number' FORMAT 99999

SELECT RULE_OWNER,
RULE_NAME,
DECLARATIVE_TYPE,
PRECEDENCE,
STEP_NUMBER
FROM DBA_XSTREAM_TRANSFORMATIONS
WHERE TRANSFORM_TYPE = 'DECLARATIVE TRANSFORMATION';

Your output looks similar to the following:

Declarative
Rule Owner      Rule Name       Type            Precedence Step Number
--------------- --------------- --------------- ---------- -----------
XSTRMADMIN      JOBS26          RENAME TABLE             4           0
XSTRMADMIN      EMPLOYEES22     ADD COLUMN               3           0

Based on this output, the ADD COLUMN transformation executes before the RENAME TABLE transformation because the step number is the same (zero) for both transformations and the ADD COLUMN transformation has the lower precedence.

The DBA_XSTREAM_TRANSFORMATIONS view can display more detailed information about each transformation based on the declarative type of the transformation. Include a WHERE clause in the query with the DECLARATIVE_TYPE equal to the type of transformation, such as ADD COLUMN, DELETE COLUMN, and so on.

For example, the previous query listed an ADD COLUMN transformation and a RENAME TABLE transformation. The following sections contain queries that display detailed information about these transformations:

- Displaying Information About ADD COLUMN Transformations

- Displaying Information About RENAME TABLE Transformations

Note:
Precedence and step number pertain only to declarative rule-based transformations. They do not pertain to subset rule transformations or custom rule-based transformations.

See Also:

- "Rule-Based Transformations"

- "Managing Declarative Rule-Based Transformations"

Displaying Information About ADD COLUMN Transformations

The query in this section displays detailed information about the ADD COLUMN declarative rule-based transformations in a database.

You use the view DBA_XTREAM_TRANSFORMATIONS to display information about the columns that are added to row LCRs with the declarative rule-based transformation procedure DBMS_XSTREAM_ADM.

To display information about ADD COLUMN transformations:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN RULE_OWNER HEADING 'Rule|Owner' FORMAT A10
COLUMN RULE_NAME HEADING 'Rule|Name' FORMAT A11
COLUMN SCHEMA_NAME HEADING 'Schema|Name' FORMAT A6
COLUMN TABLE_NAME HEADING 'Table|Name' FORMAT A9
COLUMN COLUMN_NAME HEADING 'Column|Name' FORMAT A10
COLUMN COLUMN_VALUE HEADING 'Column|Value' FORMAT A10
COLUMN COLUMN_TYPE HEADING 'Column|Type' FORMAT A8

SELECT RULE_OWNER,
RULE_NAME,
SCHEMA_NAME,
TABLE_NAME,
COLUMN_NAME,
ANYDATA.AccessDate(COLUMN_VALUE) "Value",
COLUMN_TYPE
FROM DBA_XSTREAM_TRANSFORMATIONS
WHERE DECLARATIVE_TYPE = 'ADD COLUMN';

Your output looks similar to the following:

Rule       Rule        Schema   Table    Column     Column      Column
Owner      Name        Name     Name     Name       Value       Type
----------  ----------- ------  --------- ---------- ---------- --------
XSTRMADMIN  EMPLOYEES22 HR      EMPLOYEES BIRTH_DATE            SYS.DATE

This output show the following information about the ADD COLUMN declarative rule-based transformation:

- It is specified on the employees22 rule in the xstrmadmin schema.

- It adds a column to row LCRs that involve the employees table in the hr schema.

- The column name of the added column is BIRTH_DATE.

- The value of the added column is NULL. The COLUMN_VALUE column in the ALL_XSTREAM_TRANSFORMATIONS view is type ANYDATA. In this example, because the column type is DATE, the ANYDATA.AccessDate member function is used to display the value. Use the appropriate member function to display values of other types.

- The column type of the added column is DATE.

Displaying Information About RENAME TABLE Transformations

The query in this section displays detailed information about the RENAME TABLE declarative rule-based transformations in a database.

You use the view DBA_XSTREAM_TRANSFORMATIONS to display information about declarative rule-based transformations that rename a table in a row logical change record (LCR).

To display information about RENAME TABLE transformations:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN RULE_OWNER HEADING 'Rule|Owner' FORMAT A10
COLUMN RULE_NAME HEADING 'Rule|Name' FORMAT A10
COLUMN FROM_SCHEMA_NAME HEADING 'From|Schema|Name' FORMAT A10
COLUMN TO_SCHEMA_NAME HEADING 'To|Schema|Name' FORMAT A10
COLUMN FROM_TABLE_NAME HEADING 'From|Table|Name' FORMAT A15
COLUMN TO_TABLE_NAME HEADING 'To|Table|Name' FORMAT A15

SELECT RULE_OWNER,
RULE_NAME,
FROM_SCHEMA_NAME,
TO_SCHEMA_NAME,
FROM_TABLE_NAME,
TO_TABLE_NAME
FROM DBA_XSTREAM_TRANSFORMATIONS
WHERE DECLARATIVE_TYPE = 'RENAME TABLE';

Your output looks similar to the following:

From       To         From            To
Rule       Rule       Schema     Schema     Table           Table
Owner      Name       Name       Name       Name            Name
---------- ---------- ---------- ---------- --------------- ---------------
XSTRMADMIN JOBS26     HR         HR         HR.JOBS         HR.ASSIGNMENTS

This output show the following information about the RENAME TABLE declarative rule-based transformation:

- It is specified on the jobs26 rule in the xstrmadmin schema.

- It renames the hr.jobs table in row LCRs to the hr.assignments table.

7 Troubleshooting XStream Out

This chapter describes common problems you might encounter while using XStream and explains how to solve them.

This chapter contains the following topics:

- Diagnosing Problems with XStream Out

- Problems and Solutions for XStream Out

- How to Get More Help with XStream Out

See Also:

- Chapter 3, "XStream Out Concepts"

- "XStream Use Cases"

- Chapter 4, "Configuring XStream Out"

Diagnosing Problems with XStream Out

To diagnose problems with XStream Out, use the techniques described in this section.

This section contains these topics:

- Viewing Alerts

- Using the Streams Configuration Report and Health Check Script

- Checking the Trace File and Alert Log for Problems

Viewing Alerts

An alert is a warning about a potential problem or an indication that a critical threshold has been crossed. There are two types of alerts:

- Stateless: Alerts that indicate single events that are not necessarily tied to the system state. For example, an alert that indicates that a capture aborted with a specific error is a stateless alert.

- Stateful: Alerts that are associated with a specific system state. Stateful alerts are usually based on a numeric value, with thresholds defined at warning and critical levels. For example, an alert on the current Streams pool memory usage percentage, with the warning level at 85% and the critical level at 95%, is a stateful alert.

An Oracle database generates a stateless alert under the following conditions:

- A capture process aborts.

- An outbound server aborts.

An Oracle database generates a stateful XStream alert when the Streams pool memory usage exceeds the percentage specified by the STREAMS_POOL_USED_PCT metric. You can manage this metric with the SET_THRESHOLD procedure in the DBMS_SERVER_ALERT package.

You can view alerts in Oracle Enterprise Manager Cloud Control, or you can query the following data dictionary views:

- The DBA_OUTSTANDING_ALERTS view records current stateful alerts. The DBA_ALERT_HISTORY view records stateless alerts and stateful alerts that have been cleared. For example, if the memory usage in the Streams pool exceeds the specified threshold, then a stateful alert is recorded in the DBA_OUTSTANDING_ALERTS view.

- The DBA_ALERT_HISTORY data dictionary view shows alerts that have been cleared from the DBA_OUTSTANDING_ALERTS view. For example, if the memory usage in the streams pool falls below the specified threshold, then the alert recorded in the DBA_OUTSTANDING_ALERTS view is cleared and moved to the DBA_ALERT_HISTORY view.

For example, to list the current stateful alerts, run the following query on the DBA_OUTSTANDING_ALERTS view:

COLUMN REASON HEADING 'Reason for Alert' FORMAT A35
COLUMN SUGGESTED_ACTION HEADING 'Suggested Response' FORMAT A35

SELECT REASON, SUGGESTED_ACTION
FROM DBA_OUTSTANDING_ALERTS
WHERE MODULE_ID LIKE '%XSTREAM%';

To list the stateless alerts and cleared XStream stateful alerts, run the following query on the DBA_ALERT_HISTORY view:

COLUMN REASON HEADING 'Reason for Alert' FORMAT A35
COLUMN SUGGESTED_ACTION HEADING 'Suggested Response' FORMAT A35

SELECT REASON, SUGGESTED_ACTION
FROM DBA_ALERT_HISTORY
WHERE MODULE_ID LIKE '%XSTREAM%';

Most alerts are cleared automatically when the cause of the problem disappears or is acknowledged by the database administrator. See Oracle Database 2 Day DBA for more information on clearing and purging alerts manually and with Oracle Enterprise Manager Cloud Control.

See Also:

- Oracle Database Administrator's Guide for information about alerts and for information about subscribing to the ALERT_QUE queue to receive notifications when new alerts are generated

- Oracle Database PL/SQL Packages and Types Reference for more information about the DBMS_SERVER_ALERT package

- "Configure the Streams pool"

Using the Streams Configuration Report and Health Check Script

The Streams Configuration Report and Health Check Script was designed for Oracle Streams, but it can provide important information about the XStream components in an XStream Out configuration. The report is useful to confirm that the prerequisites for XStream are met and to identify the database objects of interest for XStream. The report also analyzes the rules in the database to identify common problems with XStream rules.

The Streams Configuration Report and Health Check Script is available on the My Oracle Support (formerly Oracle MetaLink) Web site. To run the script, complete the following steps:

1. Using a Web browser, go to the My Oracle Support Web site:
http://support.oracle.com/

2. Log in to My Oracle Support.

Note:
If you are not a My Oracle Support registered user, then click Register Here and register.

3. Find the database bulletin with the following title:

Streams Configuration Report and Health Check Script

The doc ID for this bulletin is 273674.1.

4. Follow the instructions to download the script for your release, run the script, and analyze the results.

Checking the Trace File and Alert Log for Problems

Messages about each capture process and outbound server are recorded in trace files for the database in which the process is running. A local capture process runs on a source database and a downstream capture process runs on a downstream database. These trace file messages can help you to identify and resolve problems in an XStream Out configuration.

All trace files for background processes are written to the Automatic Diagnostic Repository. The names of trace files are operating system specific, but each file usually includes the name of the process writing the file.

For example, on some operating systems, the trace file name for a process is sid_xxxx_iiiii.trc, where:

- sid is the system identifier for the database

- xxxx is the name of the process

- iiiii is the operating system process number

Also, you can set the write_alert_log parameter to y for both a capture process and an outbound server. When this parameter is set to y, which is the default setting, the alert log for the database contains messages about why the capture process or outbound server stopped.

You can control the information in the trace files by setting the trace_level capture process or outbound server apply parameter using the SET_PARAMETER procedure in the DBMS_XSTREAM_ADM package.

Use the following checklist to check the trace files related to XStream:

- Capture Process Trace Files

- Logminer Trace Files

- Outbound Server Trace File

- Client Application Trace Files

See Also:

- Oracle Database Administrator's Guide for more information about trace files and the alert log, and for more information about their names and locations

- Oracle Database PL/SQL Packages and Types Reference for more information about setting the trace_level capture process parameter and the trace_level apply parameter

- Your operating system specific Oracle documentation for more information about the names and locations of trace files

Capture Process Trace Files

A capture process is an Oracle background process named CPnn, where nn can include letters and numbers. For example, on some operating systems, if the system identifier for a database running a capture process is hqdb and the capture process number is 01, then the trace file for the capture process starts with hqdb_CP01.

See Also:
"Displaying Change Capture Information About Each Capture Process" for a query that displays the capture process number of a capture process

Logminer Trace Files

Logminer trace files are useful in understanding issues with XStream Out. The logminer trace files are created when the parallelism capture process parameter is set to a value greater than 0. There are at least 3 logminer trace files that are generated and written to the Automated Diagnostic Repository.

Outbound Server Trace File

An outbound server is an Oracle background process named APnn, where nn can include letters and numbers. For example, on some operating systems, if the system identifier for a database running an outbound server is hqdb and the outbound server number is 01, then the trace file for the outbound server starts with hqdb_ap01_xxxx.trc.

An outbound server also uses other processes. Information about an outbound server might be recorded in the trace file for one or more of these processes. The process name of the reader server and apply servers is ASnn, where nn can include letters and numbers. So, on some operating systems, if the system identifier for a database running an outbound server is hqdb and the process number is 01, then the trace file that contains information about a process used by an outbound server starts with hqdb_AS01.

See Also:
"Monitoring Session Information About XStream Out Components"

Client Application Trace Files

When troubleshooting errors, isolating a problem to a key component, or identifying potential performance issues, it is a good idea to examine the trace files from all of the key sources in your XStream environment. One key source to check is the client application trace files. The client trace files are located in the directory: $ORACLE_HOME/diag/clients/.

Problems and Solutions for XStream Out

In general, you can troubleshoot XStream outbound servers in the same way that you troubleshoot Oracle Streams apply processes. In addition, an XStream Out environment includes capture processes and queues, and might include other components, such as propagations, rules, and rule-based transformations. To troubleshoot these components, see the troubleshooting documentation in Oracle Streams Concepts and Administration.

This section describes common problems and solutions specifically for XStream Out.

This section contains the following topics:

- An OCI Client Application Cannot Attach to the Outbound Server

- Changes Are Failing to Reach the Client Application in XStream Out

- The Capture Process Is Missing Required Redo Log Files

- LCRs Streaming from an Outbound Server Are Missing Extra Attributes

- The XStream Out Client Application Is Unresponsive

An OCI Client Application Cannot Attach to the Outbound Server

An XStream client application cannot attach to an outbound server using the Oracle Call Interface (OCI) OCIXStreamOutAttach() function.

The following sections describe possible problems and their solutions.

Problem 1: Client Application Not Connected as Connect User

The client application is not connected as the outbound server's connect user to the outbound server's database. The client application connected to the database as a different user.

To display information about the XStream Out servers that are accessible to the connect user:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query to determine the connect user:

SELECT SERVER_NAME,
CONNECT_USER,
CAPTURE_NAME,
SOURCE_DATABASE,
CAPTURE_USER,
QUEUE_OWNER
FROM ALL_XSTREAM_OUTBOUND;

This query displays the name of the user (connect_user) who can connect to the outbound server and process the outbound LCRs.

Solution 1

To correct problem 1:

- Modify the client application to connect to the database as the connect user before attaching to the outbound server.

Problem 2: Client Application Not Passing Service Handle

The client application is not passing a service handle to the outbound server.

Solution 2

To correct problem 2:

- Modify the client application so that it passes a service handle using OCISvcCtx and not OCIServer.

See Also:

- "XStream Out and Security"

- Oracle Call Interface Programmer's Guide

Changes Are Failing to Reach the Client Application in XStream Out

In an XStream Out configuration, database changes that should be captured and streamed to the XStream client application are not reaching the client application.

The following sections describe possible problems and their solutions.

Problem 1: Capture Process Has Fallen Behind

The capture process has fallen behind.

To determine whether the capture process has fallen behind:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture|Name' FORMAT A15
COLUMN STATE HEADING 'State' FORMAT A15
COLUMN CREATE_MESSAGE HEADING 'Last LCR|Create Time'
COLUMN ENQUEUE_MESSAGE HEADING 'Last|Enqueue Time'

SELECT CAPTURE_NAME, STATE,
TO_CHAR(CAPTURE_MESSAGE_CREATE_TIME, 'HH24:MI:SS MM/DD/YY') CREATE_MESSAGE,
TO_CHAR(ENQUEUE_MESSAGE_CREATE_TIME, 'HH24:MI:SS MM/DD/YY') ENQUEUE_MESSAGE
FROM V$XSTREAM_CAPTURE;

This query shows the current state of the capture process. This query also displays the time when the capture process last created a logical change record (LCR) and the time when the capture process last enqueued an LCR. If the times returned are before the time when the database changes were made, then the capture process must catch up and capture the changes.

Solution 1

No action is required. Normally, the capture process will catch up on its own without the need for intervention.

See Also:

- Oracle Database Reference

- Oracle Streams Replication Administrator's Guide

Problem 2: Rules or Rule-Based Transformation Excluding Changes

Rules or rule-based transformations are excluding the changes that should be captured.

Rules determine which LCRs are captured by a capture process, sent from a source queue to a destination queue by a propagation, and sent to an XStream client application by an outbound server. If the rules are not configured properly, then the client application might not receive the LCRs it should receive. The client application might also receive LCRs that it should not receive.

Rule-based transformations modify the contents of LCRs. Therefore, if the expected change data is not reaching the client application, it might be because a rule-based transformation modified the data or deleted the data. For example, a DELETE_COLUMN declarative rule-based transformation removes a column from an LCR.

Solution 2

To correct problem 2:

- Check the rules and rule-based transformations that are configured for each component in the stream from the capture process to the client application, and correct any problems.

See Also:
Oracle Streams Concepts and Administration

Problem 3: LCRs Blocked in the Stream

If the capture process has not fallen behind, and there are no problems with rules or rule-based transformations, then LCRs might be blocked in the stream for some other reason. For example, a propagation or outbound server might be disabled, a database link might be broken, or there might be another problem.

You can track an LCR through a stream using one of the following methods:

- Setting the message_tracking_frequency capture process parameter to 1 or another relatively low value
To disable LCR tracking when you use this method, set the message_tracking_frequency capture process parameter to NULL or exit the session.

- Running the SET_MESSAGE_TRACKING procedure in the DBMS_XSTREAM_ADM package
To disable LCR tracking when you use this method, set the tracking_label parameter to NULL in the SET_MESSAGE_TRACKING procedure or exit the session.

After using one of these methods, use the V$XSTREAM_MESSAGE_TRACKING view to monitor the progress of LCRs through a stream. By tracking an LCR through the stream, you can determine where the LCR is blocked.

In addition, if a propagation is used to send LCRs in the configuration, then you can check the current state of the propagation sender by running the following query:

SELECT STATE FROM V$PROPAGATION_SENDER;

You can check the current state of an outbound server by running the following query:

SELECT SERVER_NAME, STATE FROM V$XSTREAM_OUTBOUND_SERVER;

You can verify that the client application is attached to the outbound server by running the following query:

COLUMN SERVER_NAME HEADING 'Capture|Name' FORMAT A30
COLUMN STATUS HEADING 'Status' FORMAT A8

SELECT SERVER_NAME, STATUS FROM ALL_XSTREAM_OUTBOUND;

The STATUS column shows ATTACHED when the client application is attached to the outbound server.

Solution 3

To correct problem 3:

- Take the appropriate action based on the reason that the LCR is blocked. For example, if a propagation is disabled, then enable it.

See Also:

- Oracle Streams Replication Administrator's Guide for more information about tracking LCRs through a stream

- Oracle Database PL/SQL Packages and Types Reference for information about the message_tracking_frequency capture process parameter

- Oracle Streams Concepts and Administration about troubleshooting Oracle Streams components

The Capture Process Is Missing Required Redo Log Files

When a capture process is started or stopped and restarted, it might need to scan redo log files that were generated before the log file that contains the SCN that corresponds to the required checkpoint SCN. You can query the ALL_CAPTURE data dictionary view to determine the required checkpoint SCN for a capture process. It is also helpful to query the V$XSTREAM_CAPTURE and check the STATE column. The state of a capture process describes what the capture process is doing currently. In this case, you can gain additional insight as to why the capture process is missing or waiting for redo log files.

COLUMN CAPTURE_NAME HEADING 'Capture Name' FORMAT A30
COLUMN STATE HEADING 'State' FORMAT A30

SELECT CAPTURE_NAME, STATE FROM V$XSTREAM_CAPTURE;

CAPTURE_NAME            STATE
------------------      -----------------
XOUT_SRC_CAPTURE        WAITING FOR REDO

Additional information might be displayed along with the state information when you query the V$XSTREAM_CAPTURE view. The additional information can help you to determine why the capture process is waiting for redo. For example, a statement similar to the following might appear for the STATE column when you query the view:

WAITING FOR REDO: LAST SCN MINED 6700345

In this case, the output shows the last system change number (SCN) scanned by the capture process. In other cases, the output might display the redo log file name explicitly. Either way, the additional information can help you identify the redo log file for which the capture process is waiting. To correct the problem, make any missing redo log files available to the capture process.

Problem: Required Redo Log Files Were Removed

Removing required redo log files before they are scanned by a capture process causes the capture process to abort and results in the following error in a capture process trace file:

ORA-01291: missing logfile

Solution: Restore Missing Redo Log Files and Prevent Future Problems

If you see this error, then try restoring any missing redo log files and restarting the capture process. You can check the V$LOGMNR_LOGS dynamic performance view to determine the missing SCN range, and add the relevant redo log files. A capture process needs the redo log file that includes the required checkpoint SCN and all subsequent redo log files. You can query the REQUIRED_CHECKPOINT_SCN column in the ALL_CAPTURE data dictionary view to determine the required checkpoint SCN for a capture process.

If the capture process is disabled for longer than the amount of time specified in the CONTROL_FILE_RECORD_KEEP_TIME initialization parameter, then information about the missing redo log files might have been replaced in the control file. You can query the V$ARCHIVE_LOG view to see if the log file names are listed. If they are not listed, then you can register them with a ALTER DATABASE REGISTER OR REPLACE LOGFILE SQL statement.

If you are using the fast recovery area feature of Recovery Manager (RMAN) on a source database in an XStream environment, then RMAN might delete archived redo log files that are required by a capture process. RMAN might delete these files when the disk space used by the recovery-related files is nearing the specified disk quota for the fast recovery area. To prevent this problem in the future, complete one or more of the following actions:

- Increase the disk quota for the fast recovery area. Increasing the disk quota makes it less likely that RMAN will delete a required archived redo log file, but it will not always prevent the problem.

- Configure the source database to store archived redo log files in a location other than the fast recovery area. A local capture process will be able to use the log files in the other location if the required log files are missing in the fast recovery area. In this case, a database administrator must manage the log files manually in the other location.

RMAN always ensures that archived redo log files are backed up before it deletes them. If RMAN deletes an archived redo log file that is required by a capture process, then RMAN records this action in the alert log.

See Also:

- "Capture Processes"

- "XStream Out and Recovery Manager"

- "Displaying Redo Log Files That Are Required by Each Capture Process"

LCRs Streaming from an Outbound Server Are Missing Extra Attributes

LCRs streaming from an outbound server are expected to include extra attributes, but these attributes are not included in the LCRs.

LCRs can contain the following extra attributes related to database changes:

- row_id

- serial#

- session#

- thread#

- tx_name

- username

By default, a capture process does not capture these extra attributes. If you want extra attributes to be included in LCRs streamed from an outbound server to an XStream client application, but the LCRs do not contain values for extra attributes, then make sure the capture process that captures changes for the outbound server is configured to capture values for the extra attributes.

The following sections describe the possible problem and its solution.

Problem: Capture Process Not Configured to Capture Extra Attributes

The capture process is not configured to capture the required extra attributes.

To display the extra attributes currently being captured by the capture processes in a database:

1. Connect to the database running the capture process as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN CAPTURE_NAME HEADING 'Capture Process' FORMAT A30
COLUMN ATTRIBUTE_NAME HEADING 'Attribute Name' FORMAT A30

SELECT CAPTURE_NAME, ATTRIBUTE_NAME
FROM ALL_CAPTURE_EXTRA_ATTRIBUTES
WHERE INCLUDE = 'YES'
ORDER BY CAPTURE_NAME;

If an extra attribute is not displayed by this query, then it is not being captured.

Solution

To solve the problem, configure the capture process to capture the required extra attributes:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the INCLUDE_EXTRA_ATTRIBUTE procedure in the DBMS_CAPTURE_ADM package.

Example 7-1 Including the tx_name Attribute for the Capture Process xcapture

BEGIN
DBMS_CAPTURE_ADM.INCLUDE_EXTRA_ATTRIBUTE(
capture_name   => 'xcapture',
attribute_name => 'tx_name',
include        => TRUE);
END;
/

See Also:
Oracle Streams Concepts and Administration

The XStream Out Client Application Is Unresponsive

The XStream client application in an XStream Out configuration is unresponsive.

The following sections describe the possible problem and its solution.

Problem 1: Streams Pool Size Is Too Small

The Streams pool size might be too small.

To determine whether the Streams pool size is too small:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following queries at the database that contains the outbound server:

- Query the V$PROPAGATION_RECEIVER view.:

SELECT STATE FROM V$PROPAGATION_RECEIVER;

If the state is WAITING FOR MEMORY, then consider increasing the Streams pool size.

- Query the V$STREAMS_POOL_STATISTICS view.:

SELECT TOTAL_MEMORY_ALLOCATED/CURRENT_SIZE FROM V$STREAMS_POOL_STATISTICS;

If the value returned is.90 or greater, then consider increasing the Streams pool size.

Solution 1

To correct problem 1:

- Increase the Streams pool size by modifying the STREAMS_POOL_SIZE initialization parameter or by modifying other initialization parameters related to memory.

See Also:

- Oracle Database Reference

- Oracle Streams Replication Administrator's Guide

- Oracle Database Administrator's Guide for information about setting initialization parameters

Problem 2: The Maximum SGA Size for the Capture Process Is Too Small

The max_sga_size capture process parameter controls the amount of system global area (SGA) memory allocated specifically to the capture process, in megabytes.

To determine whether the maximum SGA size for the capture process is too small:

1. Connect to the database running the XStream component as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following queries at the database:

- Query the V$XSTREAM_CAPTURE view:

SELECT CAPTURE_NAME AS CAP,
SGA_USED/(1024*1024) AS USED,
SGA_ALLOCATED/(1024*1024) AS ALLOCATED,
TOTAL_MESSAGES_CAPTURED AS CAPTURED,
TOTAL_MESSAGES_ENQUEUED AS ENQUEUED
FROM V$XSTREAM_CAPTURE;

If the USED field is equal to or almost equal to the ALLOCATED field in the output, then you might need to increase the maximum SGA size for the capture process.

- Query the V$LOGMNR_SESSION view:

SELECT SESSION_NAME AS CAP,
MAX_MEMORY_SIZE/(1024*1024) AS LMMAX,
USED_MEMORY_SIZE/(1024*1024) AS LMUSED,
USED_MEMORY_SIZE/MAX_MEMORY_SIZE AS PCT
FROM V$LOGMNR_SESSION;

If the PCT field is equal to or almost equal to 1 in the output, then you might need to increase the maximum SGA size for the capture process.

Solution 2

To correct problem 2:

- Increase the maximum SGA size for the capture process by modifying the max_sga_size capture process parameter.

See Also:
"Setting a Capture Process Parameter"

Problem 3: Programming Errors

If there is enough memory in the Streams pool and the MAX_SGA_SIZE capture process parameter and apply parameter are set correctly, then check your client application for programming errors.

Solution 3

To correct problem 3:

- Correct the programming errors.

How to Get More Help with XStream Out

You can check My Oracle Support at http://support.oracle.com for more solutions to your problem.

You can visit http://www.oracle.com/support/contact.html for more information about Oracle Support.

Part III

XStream In

This part describes XStream In. This part contains the following chapters:

- Chapter 8, "XStream In Concepts,"

- Chapter 9, "Configuring XStream In,"

- Chapter 10, "Managing XStream In,"

- Chapter 11, "Monitoring XStream In,"

- Chapter 12, "Troubleshooting XStream In,"

8 XStream In Concepts

This chapter contains concepts related to XStream In.

This chapter contains these topics:

- Introduction to XStream In

- The Inbound Server

- Position of LCRs and XStream In

- XStream In and Performance Considerations

- XStream In and Security

- XStream In and Other Oracle Database Components

Introduction to XStream In

XStream In enables a remote client application to send information into an Oracle database from another system, such as a non-Oracle database or a file system. XStream In provides an efficient, transaction-based interface for sending information to an Oracle database from client applications. XStream In can consume the information coming into the Oracle database in several ways, including data replication, auditing, and change data capture. XStream In supports both OCI and Java interfaces.

When compared with OCI client applications that make DML changes to an Oracle database directly, XStream In is more efficient for near real-time, transaction-based, heterogeneous DML changes to Oracle databases.

XStream In uses the following features of Oracle Streams:

- High performance processing of DML changes, optionally with parallelism

- Apply process features such as SQL generation, conflict detection and resolution, error handling, and customized processing with apply handlers

- Streaming network transmission of information with minimal network round-trips

- Rules, rule sets, and rule-based transformations
When a custom rule-based transformation is specified on a rule used by an inbound server, the user who calls the transformation function is the apply user for the inbound server.

XStream In supports all of the data types that are supported by Oracle Streams, including LOBs, LONG, LONG RAW, and XMLType. A client application sends LOB and XMLType data to the inbound server in chunks. Several chunks comprise a single column value of LOB, LONG, LONG RAW, or XMLType data type.

See Also:

- Oracle Call Interface Programmer's Guide

- Oracle Database XStream Java API Reference

The Inbound Server

With XStream In, an Oracle Streams apply process functions as an inbound server. This section describes inbound servers.

This section contains the following topics:

- Overview of Inbound Servers

- Data Types Applied by Inbound Servers

- LCR Processing Options for Inbound Servers

- Inbound Servers and RESTRICTED SESSION

- Privileges Required by the Apply User for an Inbound Server

- Inbound Server Components

- Considerations for Inbound Servers

- The Error Queue for an Inbound Server

Overview of Inbound Servers

An inbound server is an optional Oracle background process that receives LCRs from a client application. Specifically, a client application can attach to an inbound server and send row changes, DDL changes, and procedure calls encapsulated in LCRs.

An external client application connects to the inbound server using the OCI or the Java interface. After the connection is established, the client application acts as the capture agent for the inbound server by streaming LCRs to it.

A client application can create multiple sessions. Each session can attach to only one inbound server, and each inbound server can serve only one session at a time. However, different client application sessions can connect to different inbound servers or outbound servers. A client application can detach from the inbound server whenever necessary.

Figure 8-1 shows an inbound server configuration.

Figure 8-1 XStream In Inbound Server

Note:
An inbound server uses a queue that is not shown in Figure 8-1. An inbound server's queue is only used to store error transactions.

Data Types Applied by Inbound Servers

When applying row LCRs resulting from DML changes to tables, an inbound server applies changes made to columns of the following data types:

- VARCHAR2

- NVARCHAR2

- NUMBER

- FLOAT

- LONG

- DATE

- BINARY_FLOAT

- BINARY_DOUBLE

- TIMESTAMP

- TIMESTAMP WITH TIME ZONE

- TIMESTAMP WITH LOCAL TIME ZONE

- INTERVAL YEAR TO MONTH

- INTERVAL DAY TO SECOND

- RAW

- LONG RAW

- UROWID

- CHAR

- NCHAR

- CLOB with BASICFILE or SECUREFILE storage

- NCLOB with BASICFILE or SECUREFILE storage

- BLOB with BASICFILE or SECUREFILE storage

- XMLType stored as CLOB, object relational, or as binary XML

- Object types

- The following Oracle-supplied types: ANYDATA, SDO_GEOMETRY, and media types

If XStream is replicating data for an object type, then the replication must be unidirectional, and all replication sites must agree on the names and data types of the attributes in the object type. You establish the names and data types of the attributes when you create the object type. For example, consider the following object type:

CREATE TYPE cust_address_typ AS OBJECT
(street_address     VARCHAR2(40),
postal_code        VARCHAR2(10),
city               VARCHAR2(30),
state_province     VARCHAR2(10),
country_id         CHAR(2));
/

At all replication sites, street_address must be VARCHAR2(40), postal_code must be VARCHAR2(10), city must be VARCHAR2(30), and so on.

Note:

- The maximum size of the VARCHAR2, NVARCHAR2, and RAW data types has been increased in Oracle Database 12c when the COMPATIBLE initialization parameter is set to 12.0.0 and the MAX_STRING_SIZE initialization parameter is set to EXTENDED.

- Varrays are not supported, but object type attributes can include varrays. However, primary keys cannot contain object type attributes.

- XMLType stored as a CLOB is deprecated in this release.

See Also:
Oracle Database SQL Language Reference for information about data types

LCR Processing Options for Inbound Servers

An inbound server can either apply LCRs directly or send LCRs to an apply handler for processing. Your options for LCR processing depend on whether the LCR received by an inbound server is a row LCR or a DDL LCR.

By default, an inbound server applies LCRs directly. The inbound server executes the change in the LCR on the database object identified in the LCR. The inbound server either successfully applies the change in the LCR or, if a conflict or an apply error is encountered, tries to resolve the error with a conflict handler or a user-specified procedure called an error handler.

If a conflict handler can resolve the conflict, then it either applies the LCR or it discards the change in the LCR. If an error handler can resolve the error, then it should apply the LCR, if appropriate. An error handler can resolve an error by modifying the LCR before applying it. If the conflict handler or error handler cannot resolve the error, then the inbound server places the transaction, and all LCRs associated with the transaction, into the error queue.

Instead of applying LCRs directly, you can process LCRs in a customized way with apply handlers. When you use an apply handler, an inbound server passes an LCR to a collection of SQL statements or to a user-defined PL/SQL procedure for processing. An apply handler can process the LCR in a customized way.

There are several types of apply handlers. This section uses the following categories to describe apply handlers:

Table 8-1 Characteristics of Apply Handlers

Category

Description

Mechanism

The means by which the apply handler processes LCRs. The mechanism for an apply handler is either SQL statements or a user-defined PL/SQL procedure.

Type of LCR

The type of LCR processed by the apply handler. The LCR type is either row LCR, DDL LCR, or transaction control directive.

Scope

The level at which the apply handler is set. The scope is either one operation on one table or all operations on all database objects.

Number allowed for each inbound server

The number of apply handlers of a specific type allowed for each inbound server. The number allowed is either one or many.

The following sections describe different types of apply handlers and considerations for using them:

- DML Handlers

- Error Handlers

- DDL Handlers

- Precommit Handlers

Note:
Oracle Streams Concepts and Administration for more information about these handlers and for instructions about using them

DML Handlers

DML handlers process row LCRs received by an inbound server. There are two types of DML handlers: statement DML handlers and procedure DML handlers. A statement DML handler uses a collection of SQL statements to process row LCRs, while a procedure DML handler uses a PL/SQL procedure to process row LCRs.

The following sections describe these DML handlers:

- Statement DML Handlers

- Procedure DML Handlers

Statement DML Handlers

A statement DML handler has the following characteristics:

- Mechanism: A collection of SQL statements

- Type of LCR: Row LCR

- Scope: One operation on one table

- Number allowed for each inbound server: Many, and many can be specified for the same operation on the same table

Each SQL statement included in a statement DML handler has a unique execution sequence number. When a statement DML handler is invoked, it executes its statements in order from the statement with the lowest execution sequence number to the statement with the highest execution sequence number. An execution sequence number can be a positive number, a negative number, or a decimal number.

For each table associated with an inbound server, you can set a separate statement DML handler to process each of the following types of operations in row LCRs:

- INSERT

- UPDATE

- DELETE

A statement DML handler is invoked when the inbound server receives a row LCR that performs the specified operation on the specified table. For example, the hr.employees table can have one statement DML handler to process INSERT operations and a different statement DML handler to process UPDATE operations. Alternatively, the hr.employees table can use the same statement DML handler for each type of operation.

You can specify multiple statement DML handlers for the same operation on the same table. In this case, these statement DML handlers can execute in any order, and each statement DML handler receives a copy of the original row LCR that was received by the inbound server.

Procedure DML Handlers

A procedure DML handler has the following characteristics:

- Mechanism: A user-defined PL/SQL procedure

- Type of LCR: Row LCR

- Scope: One operation on one table

- Number allowed for each inbound server: Many, but only one can be specified for the same operation on the same table

For each table associated with an inbound server, you can set a separate procedure DML handler to process each of the following types of operations in row LCRs:

- INSERT

- UPDATE

- DELETE

- LOB_UPDATE

A procedure DML handler is invoked when the inbound server receives a row LCR that performs the specified operation on the specified table. For example, the hr.employees table can have one procedure DML handler to process INSERT operations and a different procedure DML handler to process UPDATE operations. Alternatively, the hr.employees table can use the same procedure DML handler for each type of operation.

The PL/SQL procedure can perform any customized processing of row LCRs. For example, if you want each insert into a particular table at the source database to result in inserts into multiple tables at the destination database, then you can create a user-defined PL/SQL procedure that processes INSERT operations on the table to accomplish this. Unlike statement DML handlers, procedure DML handlers can modify the column values in row LCRs.

Error Handlers

An error handler has the following characteristics:

- Mechanism: A user-defined PL/SQL procedure

- Type of LCR: Row LCR

- Scope: One operation on one table

- Number allowed for each inbound server: Many, but only one can be specified for the same operation on the same table

An error handler is similar to a procedure DML handler. The difference between the two is that an error handler is invoked only if an apply error results when an inbound server tries to apply a row LCR for the specified operation on the specified table.

Note:
Statement DML handlers cannot be used as error handlers.

DDL Handlers

A DDL handler has the following characteristics:

- Mechanism: A user-defined PL/SQL procedure

- Type of LCR: DDL LCR

- Scope: All DDL LCRs received by the inbound server

- Number allowed for each inbound server: One

The user-defined PL/SQL procedure can perform any customized processing of DDL LCRs. For example, to log DDL changes before applying them, you can create a procedure that processes DDL operations to accomplish this.

Precommit Handlers

A precommit handler has the following characteristics:

- Mechanism: A user-defined PL/SQL procedure

- Type of LCR: Commit directive for transactions that include row LCRs

- Scope: All row LCRs with commit directives received by the inbound server

- Number allowed for each inbound server: One

You can use a precommit handler to audit commit directives for LCRs. A commit directive is a transaction control directive that contains a COMMIT. A precommit handler is a user-defined PL/SQL procedure that can receive the commit information for a transaction and process the commit information in any customized way. A precommit handler can work with a statement DML handler or procedure DML handler.

For example, a precommit handler can improve performance by caching data for the length of a transaction. This data can include cursors, temporary LOBs, data from a message, and so on. The precommit handler can release or execute the objects cached by the handler when a transaction completes.

Inbound Servers and RESTRICTED SESSION

When restricted session is enabled during system startup by issuing a STARTUP RESTRICT statement, inbound servers do not start, even if they were running when the database shut down. When the restricted session is disabled, each inbound server that was not stopped is started.

When restricted session is enabled in a running database by the SQL statement ALTER SYSTEM ENABLE RESTRICTED SESSION, it does not affect any running inbound servers. These inbound servers continue to run and send LCRs to an XStream client application. If a stopped inbound server is started in a restricted session, then the inbound server does not actually start until the restricted session is disabled.

Inbound Server Components

An inbound server consists of the following subcomponents:

- A reader server that receives LCRs from an XStream client application. The reader server is a process that computes dependencies between logical change records (LCRs) and assembles LCRs into transactions. The reader server then returns the assembled transactions to the coordinator process.
You can view the state of the reader server for an inbound server by querying the V$XSTREAM_APPLY_READER dynamic performance view. See Oracle Database Reference.

- A coordinator process that gets transactions from the reader server and passes them to apply servers. The coordinator process name is APnn, where nn can include letters and numbers. The coordinator process is an Oracle background process.
You can view the state of a coordinator process by querying the V$XSTREAM_APPLY_COORDINATOR dynamic performance view. See Oracle Database Reference.

- One or more apply servers that apply LCRs to database objects as DML or DDL statements or that pass the LCRs to their appropriate apply handlers. Apply servers can also enqueue LCRs into the persistent queue portion of a queue specified by the DBMS_APPLY_ADM.SET_ENQUEUE_DESTINATION procedure. Each apply server is a process. If an apply server encounters an error, then it then tries to resolve the error with a user-specified conflict handler or error handler. If an apply server cannot resolve an error, then it rolls back the transaction and places the entire transaction, including all of its LCRs, in the error queue.
When an apply server commits a completed transaction, this transaction has been applied. When an apply server places a transaction in the error queue and commits, this transaction also has been applied.

You can view the state of each apply server for an inbound server by querying the V$XSTREAM_APPLY_SERVER dynamic performance view. See Oracle Database Reference.

The reader server and the apply server process names are ASnn, where nn can include letters and numbers. If a transaction being handled by an apply server has a dependency on another transaction that is not known to have been applied, then the apply server contacts the coordinator process and waits for instructions. The coordinator process monitors all of the apply servers to ensure that transactions are applied and committed in the correct order.

Considerations for Inbound Servers

The following are considerations for XStream inbound servers:

- You can control a DML or DDL trigger's firing property using the SET_TRIGGER_FIRING_PROPERTY procedure in the DBMS_DDL package. This procedure lets you specify whether a trigger always fires, fires once, or fires for inbound server changes only. When a trigger is set to fire once, it fires for changes made by a user process, but it does not fire for changes made by an inbound server. A trigger's firing property works the same for apply processes and inbound servers. See Oracle Streams Concepts and Administration.

- An inbound server ignores the setting for the ignore_transaction apply parameter because LCRs sent to the inbound server by the client application might not have transaction ID values.

- An inbound server ignores the setting for the maximum_scn apply parameter because LCRs sent to the inbound server by the client application might not have SCN values.

See Also:
Oracle Database PL/SQL Packages and Types Reference for more information about apply parameters

The Error Queue for an Inbound Server

The error queue contains all of the current apply errors for a database. If there are multiple inbound servers in a database, then the error queue contains the apply errors for each inbound server.

Trusted users can view apply errors by querying the DBA_APPLY_ERROR data dictionary view or by using Oracle Enterprise Manager Cloud Control. The DBA_APPLY_ERROR data dictionary view enables the trusted user to see information about apply errors for other users. Untrusted users can view apply errors by querying the ALL_APPLY_ERROR data dictionary view. This view shows only apply errors for the untrusted user.

Also, trusted users can view more detailed information about apply errors by querying the DBA_APPLY_ERROR_MESSAGES data dictionary view. Untrusted users can view more detailed information about apply errors by querying the ALL_APPLY_ERROR_MESSAGES data dictionary view. These views include information about the row that caused the error in an error transaction.

The error queue stores information about transactions that could not be applied successfully by the inbound server running in a database. A transaction can include many LCRs. When an unhandled error occurs during apply, an inbound server automatically moves all of the LCRs in the transaction that satisfy the inbound server's rule sets to the error queue.

You can correct the condition that caused an error and then reexecute the transaction that caused the error. For example, you might modify a row in a table to correct the condition that caused an error.

When the condition that caused the error has been corrected, you can either reexecute the transaction in the error queue using the EXECUTE_ERROR or EXECUTE_ALL_ERRORS procedure, or you can delete the transaction from the error queue using the DELETE_ERROR or DELETE_ALL_ERRORS procedure. These procedures are in the DBMS_APPLY_ADM package.

When you reexecute a transaction in the error queue, you can specify that the transaction be executed either by the user who originally placed the error in the error queue or by the user who is reexecuting the transaction. Also, the current tag for the inbound server is used when you reexecute a transaction in the error queue.

A reexecuted transaction uses any relevant apply handlers and conflict resolution handlers. If, to resolve the error, a row LCR in an error queue must be modified before it is executed, then you can configure a procedure DML handler to process the row LCR that caused the error in the error queue. In this case, the DML handler can modify the row LCR to avoid a repetition of the same error. The row LCR is passed to the DML handler when you reexecute the error containing the row LCR. For example, a statement DML handler might insert different values than the ones present in an insert row LCR, while a procedure DML handler might modify one or more columns in the row LCR to avoid a repetition of the same error.

Position of LCRs and XStream In

A client application streams LCRs to an XStream In inbound server. This section describes concepts related to the LCR positions for an inbound server.

Each position must be encoded in a format (such as base-16 encoding) that supports byte comparison. The position is essential to the total order of the transaction stream sent by client applications using the XStream In interface.

The following positions are important for inbound servers:

- The applied low position indicates that the LCRs less than or equal to this value have been applied.
An LCR is applied by an inbound server when the LCR has either been executed, sent to an apply handler, or moved to the error queue.

- The spill position indicates that the LCRs with positions less than or equal to this value have either been applied or spilled from memory to hard disk.

- The applied high position indicates the highest position of an LCR that has been applied.
When the commit_serialization apply parameter is set to DEPENDENT_TRANSACTIONS for an inbound server, an LCR with a higher commit position might be applied before an LCR with a lower commit position. When this happens, the applied high position is different from the applied low position.

- The processed low position is the higher value of either the applied low position or the spill position.
The processed low position is the position below which the inbound server no longer requires any LCRs. This position corresponds with the oldest SCN for an Oracle Streams apply process that applies changes captured by a capture process.

The processed low position indicates that the LCRs with positions less than or equal to this position have been processed by the inbound server. If the client re-attaches to the inbound server, then it must send only LCRs with positions greater than the processed low position because the inbound server discards any LCRs with positions less than or equal to the processed low position.

If the client application stops abnormally, then the connection between the client application and the inbound server is automatically broken. Upon restart, the client application retrieves the processed low position from the inbound server and instructs its capture agent to retrieve changes starting from this processed low position.

To limit the recovery time of a client application using the XStream In interface, the client application can send activity, such as empty transactions, periodically to the inbound server. Row LCRs can include commit transaction control directives. When there are no LCRs to send to the server, the client application can send a row LCR with a commit directive to advance the inbound server's processed low position. This activity acts as an acknowledgment so that the inbound server's processed low position is advanced.

Example 8-1 Advancing the Processed Low Position of an Inbound Server

Consider a client application and an external data source. The client application sends changes made to the hr.employees table to the inbound server for processing, but the external data source includes many other tables, including the oe.orders table.

Assume that the following changes are made to the external data source:

Position

Change

Client Application Activity

1

Insert into the hr.employees table

Send row LCR including the change to the inbound server

2

Insert into the oe.orders table

None

3

Commit

Send a row LCR with a commit directive to inbound server

4

Insert into the oe.orders table

None

5

Update the oe.orders table

None

6

Commit

None

7

Commit

None

...

... (Activity on the external data source, but no changes to the hr.employees table)

None

100

Insert into the oe.orders table

None

101

Commit

None

The client application gets the changes from the external data source, generates appropriate LCRs, and sends the LCRs to the inbound server. Therefore, the inbound server receives the following LCRs:

- Row LCR for position 1

- Row LCR for position 3

After position 3, there are no relevant changes to send to the inbound server. If the inbound server restarts when the client application has processed all the changes up to position 101, then, after restarting, the client application must recheck all of the external database changes from position 4 forward. The rechecks are required because the inbound server's processed low position is 3.

Instead, assume that the client application sends commits to the inbound server periodically, even when there are no relevant changes to the hr.employees table:

Position

Change

Client Application Activity

1

Insert into the hr.employees table

Send row LCR including the change to the inbound server

2

Insert into the oe.orders table

None

3

Commit

Send a row LCR with a commit directive to inbound server

4

Insert into the oe.orders table

None

5

Update the oe.orders table

None

6

Commit

None

7

Commit

None

...

... (Activity on the external data source, but no changes to the hr.employees table)

Send several row LCRs, each one with a commit directive, to the inbound server

100

Insert into the oe.orders table

None

101

Commit

Send a row LCR with a commit directive to the inbound server

In this case, the inbound server moves its processed low position to 101 when it has processed all of the row LCRs sent by the client application. If the inbound server restarts, its processed low position is 101, and the client application does not need to check all of the changes back to position 3.

The sample applications in Appendix A, "Sample XStream Client Application" include code that sends a row LCR with a commit directive to an inbound server. These commit directives are sometimes called "ping LCRs." Search for the word "ping" in the sample XStream client applications to find the parts of the applications that include this code.

See Also:

- "Position Order in an LCR Stream"

- "Displaying the Position Information for an Inbound Server"

XStream In and Performance Considerations

This section contains the following topics related to XStream In and performance:

- Optimizing XStream In Performance for Large Transactions

- Avoiding Potential Bottlenecks in Transaction Tracking

- Optimizing Transaction Apply Scheduling

Optimizing XStream In Performance for Large Transactions

For small transactions, XStream In does not begin to apply the logical change records (LCRs) until the inbound server receives a commit LCR for the transaction from the source. As a performance optimization, an inbound server can use eager apply to begin to apply large transactions before it receives the commit LCR. The eager_size apply parameter controls the minimum number of LCRs received by the inbound server before eager apply begins. When the number of LCRs in a transaction exceeds the value of the eager_size apply parameter, the inbound server begins to apply the LCRs. The default value for this parameter is 9500. You can modify the parameter value to optimize XStream In performance in your environment.

Large transactions may require additional apply servers to apply the LCRs. After eager apply starts for a transaction, an inbound server can automatically create additional apply servers to apply the LCRs. The max_parallelism apply parameter controls the maximum number of apply servers for an inbound server.

If an inbound server automatically creates additional apply servers, and some of them are idle for a period of time, then XStream In determines that they are no longer necessary and removes them automatically. However, the number of apply servers never goes below the value specified by the parallelism apply parameter. Any statistics for these apply servers are aggregated as apply server 0 (zero).

For an inbound server to use eager apply for large transactions, the value of the eager_size apply parameter must be less than the value of the txn_lcr_spill_threshold apply parameter. When the value of txn_lcr_spill_threshold is lower than eager_size, a transaction spills to disk before eager apply begins, and a an inbound server cannot use eager apply for a transaction that has spilled to disk.

See Also:

- Oracle Database PL/SQL Packages and Types Reference

- "Managing Eager Errors Encountered by an Inbound Server"

Avoiding Potential Bottlenecks in Transaction Tracking

XStream In keeps track of the changes it is applying to the database to avoid reapplying transactions when an inbound server is restarted. When the optimize_progress_table apply parameter is set to TRUE, the default, XStream In tracks its progress in the redo log. Use of the redo log avoids the potential bottleneck and contention caused by DML changes in the progress table.

When the optimize_progress_table parameter is set to FALSE, XStream In uses a table for tracking. In high volume environments, this table can be a potential bottleneck.

The apply database must be in archive log mode before apply tracking can be done in the redo log. If the optimize_progress_table parameter is set to TRUE but the apply database is not in archive log mode, then the setting of optimize_progress_table is ignored and XStream In uses a table for tracking.

See Also:
Oracle Database PL/SQL Packages and Types Reference

Optimizing Transaction Apply Scheduling

When the constraints on the target tables match the constraints on the source tables, you can optimize dependency computation by setting the compute_lcr_dep_on_arrival apply parameter for an inbound server to Y. If the constraints do not match, then set this apply parameter to N, the default.

If this apply parameter is set to Y, then the dependencies are computed as the LCRs for the transaction are received. If this apply parameter is set to N, then the dependencies are computed only after all the LCRs for a committed transaction are received.

Regardless of compute_lcr_dep_on_arrival apply parameter setting, the before image of the key columns must be available in the LCRs received by the inbound server. Key columns include primary key columns, foreign key column, and unique constraint columns. In an XStream configuration in which an inbound server applies changes captured by a capture process in an XStream Out configuration, supplemental logging ensures that the required information is in the LCRs.

See Also:

- "If Required, Configure Supplemental Logging"

- Oracle Database PL/SQL Packages and Types Reference

XStream In and Security

This section contains the following topics related to XStream In and security:

- The XStream In Client Application and Security

- XStream In Component-Level Security

- Privileges Required by the Apply User for an Inbound Server

See Also:

- "XStream Security Models"

- Oracle Database PL/SQL Packages and Types Reference

The XStream In Client Application and Security

XStream In allows an application to send LCRs to an inbound server, and an inbound server can apply the database changes in the LCRs to the database. Java and OCI client applications must connect to an Oracle database before attaching to an XStream inbound server created on that database. The connected user must be the same as the apply user configured for the inbound server. Otherwise, an error is raised.

The XStream Java layer API relies on Oracle JDBC security because XStream accepts the Oracle JDBC connection instance created by client applications in the XStream attach method in the XStreamIn class. The connected user is validated as an XStream user.

See Also:

- Oracle Call Interface Programmer's Guide for information about the OCI interface for XStream

- Oracle Database XStream Java API Reference for information about the Java interface for XStream

XStream In Component-Level Security

All the components of the XStream In configuration run as the same user. This user is the apply user for the inbound server. This user can be either a trusted user with a high level of privileges or it can be an untrusted user that has only the privileges necessary for performing certain tasks.

The security model of the XStream administrator also determines the data dictionary views that this user can query to monitor the XStream configuration. The trusted administrator can monitor XStream with DBA_ views. The untrusted administrator can monitor XStream with ALL_ views.

You create an XStream administrator using the GRANT_ADMIN_PRIVILEGE procedure in the DBMS_XSTREAM_AUTH package. When you run this procedure to create an XStream administrator for XStream In, the privilege_type parameter determines the type of privileges granted to the user:

- Specify APPLY for the privilege_type parameter if the XStream administrator manages only an XStream In configuration on the database.

- Specify * for the privilege_type parameter if the XStream administrator manages both an XStream Out and an XStream In configuration on the database.

The GRANT_ADMIN_PRIVILEGE procedure grants privileges for Oracle-supplied views and packages that are required to run components in an XStream In or XStream Out configuration. This procedure does not grant privileges on database objects owned by users. If such privileges are required, then they must be granted separately.

See Also:
"Configure an XStream Administrator" for detailed information about configuring an XStream administrator

Privileges Required by the Apply User for an Inbound Server

An inbound server applies LCRs in the security domain of its apply user. The inbound server receives LCRs from an XStream client application and applies the LCRs that satisfy the inbound server's rule sets. The apply user can apply LCRs directly to database objects. In addition, the apply user runs all custom rule-based transformations specified by the rules in these rule sets. The apply user also runs user-defined apply handlers. XStream In does not assume that the apply user for the inbound server is trusted.

The apply user must have the necessary privileges to apply changes, including the following privileges:

- The required privileges to apply data manipulation language (DML) changes to tables in other schemas (when the inbound server receives DML changes to tables in other schemas)

- The required privileges to apply data definition language (DDL) changes to the database (when the inbound server receives DDL changes)

- EXECUTE privilege on the rule sets used by the inbound server

- EXECUTE privilege on all custom rule-based transformation functions specified for rules in the positive rule set

- EXECUTE privilege on any apply handlers

An inbound server can be associated with only one user, but one user can be associated with many inbound servers.

Grant privileges to the apply user with the DBMS_XSTREAM_AUTH package by specifying APPLY for the privilege_type parameter in the GRANT_ADMIN_PRIVILEGE procedure.

See Also:

- "Configure an XStream Administrator"

- "Changing the Apply User for an Inbound Server"

- Oracle Database XStream Guide for more information about the GRANT_ADMIN_PRIVILEGE procedure

XStream In and Other Oracle Database Components

This section describes how XStream In works with other Oracle Database components.

This section contains the following topics:

- XStream In and Oracle Real Application Clusters

- XStream In and Flashback Data Archive

- XStream In and Transportable Tablespaces

- XStream In and a Multitenant Environment

XStream In and Oracle Real Application Clusters

You can configure an inbound server to apply changes in an Oracle Real Application Clusters (Oracle RAC) environment. The inbound server runs in the Oracle RAC instance where you connected. In the event that this instance fails, you can connect to a surviving instance and start the inbound server again.

See Also:

- The Inbound Server

- Oracle Real Application Clusters Administration and Deployment Guide

XStream In and Flashback Data Archive

Inbound servers can apply changes encapsulated in logical change records (LCRs) to tables in a flashback data archive.

Inbound servers also support the following DDL statements:

- CREATE FLASHBACK ARCHIVE

- ALTER FLASHBACK ARCHIVE

- DROP FLASHBACK ARCHIVE

- CREATE TABLE with a FLASHBACK ARCHIVE clause

- ALTER TABLE with a FLASHBACK ARCHIVE clause

See Also:

- The Inbound Server

- Oracle Database Development Guide for information about flashback data archive

XStream In and Transportable Tablespaces

This section describes how to import data into databases involved in an XStream replication environment using transportable tablespaces.The instructions in this section apply when the following conditions are met:

- The replication configuration is one in which an inbound server applies changes captured by a capture process in an XStream Out configuration.

- The data being imported with transportable tablespaces must be included in each database in the replication environment.

- After the import operation is complete, changes to the imported data will be replicated.

In addition, the rules should instruct the replication environment to avoid replicating tagged LCRs.

When these conditions are met, complete the following steps:

1. Stop replication.

2. Use transportable tablespaces to import the data into each database in the replication environment.

3. Restart replication.

See Also:

- Oracle Database Administrator's Guide for more information about transportable tablespaces

- Oracle Streams Replication Administrator's Guide for information about tagged LCRs

XStream In and a Multitenant Environment

A multitenant environment enables an Oracle database to contain a portable set of schemas, objects, and related structures that appears logically to an application as a separate database. This self-contained collection is called a pluggable database (PDB). A multitenant container database (CDB) contains PDBs. This section assumes that you understand multitenant architecture concepts. See Oracle Database Concepts for information.

In a CDB, the inbound server is restricted to receiving LCRs from one source database and only executing changes in the current container (one PDB or the root). A single inbound server cannot apply changes to more than one container in a CDB.

When the inbound server is in the root, the apply user must be a common user. When the inbound server is in a PDB, the apply user can be a common user or a local user.

See Also:

- "System-Created Rules and a Multitenant Environment"

- Oracle Database Administrator's Guide

9 Configuring XStream In

This chapter describes configuring the Oracle Database components that are used by XStream.

This chapter contains these topics:

- Preparing for XStream In

- Configuring XStream In

See Also:

- Chapter 3, "XStream Out Concepts"

- "XStream Use Cases"

- Oracle Call Interface Programmer's Guide

- Oracle Database XStream Java API Reference

Preparing for XStream In

Ensure that the following prerequisites are met before configuring XStream In:

- Configure an XStream Administrator

- Set the Relevant Initialization Parameters

- Configure the Streams pool

- If Required, Specify Supplemental Logging at the Source Database

Configure an XStream Administrator

An XStream administrator configures and manages XStream components in an XStream In environment. This section describes configuring an XStream administrator by granting a user the appropriate privileges. You must configure an XStream administrator in each Oracle database included in the XStream configuration.

If you are configuring XStream In in a multitenant container database (CDB), then configure the XStream administrator in the container that will run the inbound server. This container can be the root or a pluggable database (PDB). See "XStream In and a Multitenant Environment" for information about using XStream In in a CDB.

Prerequisites

Before configuring an XStream administrator, ensure that the following prerequisites are met:

- Ensure that you can log in to each database in the XStream configuration as an administrative user who can create users, grant privileges, and create tablespaces.

- Decide between the trusted user model and untrusted user model for security. See XStream Security Models for more information.

- Identify a user who will be the XStream administrator. Either create a new user with the appropriate privileges or grant these privileges to an existing user.
Do not use the SYS or SYSTEM user as an XStream administrator, and ensure that the XStream administrator does not use the SYSTEM tablespace as its default tablespace.

- If a new tablespace is required for the XStream administrator, then ensure that there is enough disk space on each computer system in the XStream configuration for the tablespace. The recommended size of the tablespace is 25 MB.

Assumptions

This section makes the following assumptions:

- The username of the XStream administrator is xstrmadmin for a non-CDB. In a CDB, when the XStream administrator is a common user, the username of the XStream administrator is c##xstrmadmin. When the XStream administrator in a CDB is a local user in a PDB, the username of the XStream administrator is xstrmadmin.

- The tablespace used by the XStream administrator is xstream_tbs.

To configure an XStream administrator:

1. In SQL*Plus, connect as an administrative user who can create users, grant privileges, and create tablespaces. Remain connected as this administrative user for all subsequent steps.

See Also:
Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus

2. Either create a tablespace for the XStream administrator or use an existing tablespace.
This tablespace stores any objects created in the XStream administrator's schema.

For example, the following statement creates a new tablespace for the XStream administrator:

CREATE TABLESPACE xstream_tbs DATAFILE '/usr/oracle/dbs/xstream_tbs.dbf'
SIZE 25M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED;

If you are creating an XStream administrator as a common user in a CDB, then you must create the tablespace in the root and in all PDBs. The tablespace is required in all PDBs because a common user must have access to the tablespace in any PDB.

3. Create a new user to act as the XStream administrator or identify an existing user.
For example, to create a user named xstrmadmin and specify that this user uses the xstream_tbs tablespace, run the following statement:

CREATE USER xstrmadmin IDENTIFIED BY password
DEFAULT TABLESPACE xstream_tbs
QUOTA UNLIMITED ON xstream_tbs;

If you are creating an XStream administrator in a CDB and the inbound server is in the root, then the XStream administrator must be a common user.

If you are creating an XStream administrator in a CDB and the inbound server is in a PDB, then the XStream administrator can be a common user or a local user. Oracle recommends configuring a common user as the XStream administrator even when the inbound server is in a PDB.

To create a common user, include the CONTAINER=ALL clause in the CREATE USER statement when the current container is the root:

CREATE USER c##xstrmadmin IDENTIFIED BY password
DEFAULT TABLESPACE xstream_tbs
QUOTA UNLIMITED ON xstream_tbs
CONTAINER=ALL;

Note:
Enter an appropriate password for the administrative user.

See Also:
Oracle Database Security Guide for guidelines about choosing passwords

4. Grant CREATE SESSION privilege to the XStream administrator.
If you created a new user to act as the XStream administrator, then grant this user CREATE SESSION privilege.

For example, to grant CREATE SESSION privilege to user xstrmadmin, run the following statement:

GRANT CREATE SESSION TO xstrmadmin;

If you are creating an XStream administrator as a common user in a CDB, then grant CREATE SESSION privilege and SET CONTAINER privilege to the XStream administrator, and include the CONTAINER=ALL clause in the statement.

For example, to grant these privileges to user xstrmadmin in a CDB, run the following statement:

GRANT CREATE SESSION, SET CONTAINER TO c##xstrmadmin CONTAINER=ALL;

5. Run the GRANT_ADMIN_PRIVILEGE procedure in the DBMS_XSTREAM_AUTH package.
A user must have explicit EXECUTE privilege on a package to execute a subprogram in the package inside of a user-created subprogram, and a user must have explicit READ or SELECT privilege on a data dictionary view to query the view inside of a user-created subprogram. These privileges cannot be granted through a role. You can run the GRANT_ADMIN_PRIVILEGE procedure to grant such privileges to the XStream administrator, or you can grant them directly.

Depending on the parameter settings for the GRANT_ADMIN_PRIVILEGE procedure, it can grant the appropriate privileges for a trusted or untrusted XStream administrator, and it can grant privileges in a non-CDB or a CDB. Table 9-1 describes key parameter settings for each case.

Table 9-1 Key Parameter Settings for GRANT_ADMIN_PRIVILEGE

Type of XStream Administrator

grant_select_privileges Parameter Setting

container Parameter Setting

Trusted in a non-CDB

TRUE

CURRENT (default)

Untrusted in a non-CDB

FALSE (default)

CURRENT (default)

Trusted in a CDB

TRUE

ALL

Untrusted in a CDB

FALSE (default)

ALL

Example 9-1 Granting Privileges to a Trusted XStream Administrator in a Non-CDB Without Generating a Script

BEGIN
DBMS_XSTREAM_AUTH.GRANT_ADMIN_PRIVILEGE(
grantee                 => 'xstrmadmin',
privilege_type          => 'APPLY',
grant_select_privileges => TRUE);
END;
/

Example 9-2 Granting Privileges to a Trusted XStream Administrator in a Non-CDB and Generating a Script

The directory specified in the directory_name parameter must exist and must be accessible to the current user.

BEGIN
DBMS_XSTREAM_AUTH.GRANT_ADMIN_PRIVILEGE(
grantee                 => 'xstrmadmin',
privilege_type          => 'APPLY',
grant_select_privileges => TRUE,
do_grants               => TRUE,
file_name               => 'grant_xstrm_privs.sql',
directory_name          => 'xstrm_dir');
END;
/

Example 9-3 Granting Privileges to an Untrusted XStream Administrator in a Non-CDB Without Generating a Script

BEGIN
DBMS_XSTREAM_AUTH.GRANT_ADMIN_PRIVILEGE(
grantee                 => 'xstrmadmin',
privilege_type          => 'APPLY',
grant_select_privileges => FALSE);
END;
/

Example 9-4 Granting Privileges to a Trusted XStream Administrator in a CDB Without Generating a Script

In this example, the XStream administrator is a common user.

BEGIN
DBMS_XSTREAM_AUTH.GRANT_ADMIN_PRIVILEGE(
grantee                 => 'c##xstrmadmin',
privilege_type          => 'APPLY',
grant_select_privileges => TRUE,
container               => 'ALL');
END;
/

Note:
For any scenario, when the XStream administrator must manage both an XStream Out and an XStream In configuration on the database, specify * for the privilege_type parameter.

See Also:
Oracle Database PL/SQL Packages and Types Reference

6. If necessary, grant additional privileges to the XStream administrator.
See "Granting Additional Privileges to the XStream Administrator".

7. Repeat all of the previous steps at each Oracle database in the environment that will use XStream.

Granting Additional Privileges to the XStream Administrator

Grant any of the following additional privileges to the XStream Administrator if necessary:

- If you plan to use Oracle Enterprise Manager Cloud Control to manage databases with XStream components, then the XStream administrator must be trusted and must be granted DBA role. You must also configure the XStream administrator to be an Oracle Enterprise Manager administrative user. Doing so grants additional privileges required by Oracle Enterprise Manager Cloud Control, such as the privileges required to run Oracle Enterprise Manager Cloud Control jobs. See the Oracle Enterprise Manager Cloud Control online help for information about creating Oracle Enterprise Manager administrative users.

- If no apply user is specified for an inbound server, then grant the XStream administrator the necessary privileges to perform DML and DDL changes on the apply objects owned by other users. If an apply user is specified, then the apply user must have these privileges. These privileges can be granted directly or through a role.

- If no apply user is specified for an inbound server, then grant the XStream administrator EXECUTE privilege on any PL/SQL subprogram owned by another user that is executed by an inbound server. These subprograms can be used in apply handlers or error handlers. If an apply user is specified, then the apply user must have these privileges. These privileges must be granted directly. They cannot be granted through a role.

- Grant the XStream administrator EXECUTE privilege on any PL/SQL function owned by another user that is specified in a custom rule-based transformation for a rule used by an inbound server. For an inbound server, if an apply user is specified, then the apply user must have these privileges. These privileges must be granted directly. They cannot be granted through a role.

- If the XStream administrator does not own the queue used by an inbound server and is not specified as the queue user for the queue when the queue is created, then the XStream administrator must be configured as a secure queue user of the queue if you want the XStream administrator to be able to enqueue LCRs into or dequeue LCRs from the queue. The XStream administrator might also need ENQUEUE or DEQUEUE privileges on the queue, or both. See Oracle Streams Concepts and Administration for information about managing queues.

- Grant the XStream administrator EXECUTE privilege on any object types that the XStream administrator might need to access. These privileges can be granted directly or through a role.

- If you are using Oracle Database Vault, then the following additional privileges are required:

- The apply user for an inbound server must be authorized to apply changes to realms that include replicated database objects. The replicated database objects are the objects to which the inbound server applies changes.
To authorize an apply user for a realm, run the DVSYS.DBMS_MACADM.ADD_AUTH_TO_REALM procedure and specify the realm and the apply user. For example, to authorize apply user xstrmadmin for the sales realm, run the following procedure:

BEGIN
DVSYS.DBMS_MACADM.ADD_AUTH_TO_REALM(
realm_name  => 'sales',
grantee     => 'xstrmadmin');
END;
/

- The user who creates or alters an inbound server must be granted the BECOME USER system privilege.
Granting the BECOME USER system privilege to the user who performs these actions is not required if Oracle Database Vault is not installed. You can revoke the BECOME USER system privilege from the user after the completing one of these actions, if necessary.

See Oracle Database Vault Administrator's Guide.

Set the Relevant Initialization Parameters

Some initialization parameters are important for the configuration, operation, reliability, and performance of XStream inbound servers. Set these parameters appropriately.

The following requirements apply to XStream inbound servers:

- Ensure that the PROCESSES initialization parameter is set to a value large enough to accommodate the inbound server background processes and all of the other Oracle Database background processes.

- Ensure that the SESSIONS initialization parameter is set to a value large enough to accommodate the sessions used by the inbound server background processes and all of the other Oracle Database sessions.

Configure the Streams pool

The Streams pool is a portion of memory in the System Global Area (SGA) that is used by both Oracle Streams and XStream components. The Streams pool stores buffered queue LCRs in memory, and it provides memory for inbound servers.

The following are considerations for configuring the Streams pool:

- At least 300 MB of memory is required for the Streams pool.

- The best practice is to set the STREAMS_POOL_SIZE initialization parameter explicitly to the desired Streams pool size.

- After XStream In is configured, you can use the max_sga_size apply parameter to control the amount of SGA memory allocated specifically to an inbound server.

- Ensure that there is enough space in the Streams pool at each database to run XStream components and to store LCRs and run the components properly.

- The Streams pool is initialized the first time an inbound server is started.

The Streams pool size is the value specified by the STREAMS_POOL_SIZE parameter, in bytes, if the following conditions are met:

- The MEMORY_TARGET, MEMORY_MAX_TARGET, and SGA_TARGET initialization parameters are all set to 0 (zero).

- The STREAMS_POOL_SIZE initialization parameter is set to a nonzero value.

The Automatic Shared Memory Management feature automatically manages the size of the Streams pool when the following conditions are met:

- The MEMORY_TARGET and MEMORY_MAX_TARGET initialization parameters are both set to 0 (zero).

- The SGA_TARGET initialization parameter is set to a nonzero value.

If you are using Automatic Shared Memory Management and the STREAMS_POOL_SIZE initialization parameter also is set to a nonzero value, then Automatic Shared Memory Management uses this value as a minimum for the Oracle Streams pool. You can set a minimum size if your environment needs a minimum amount of memory in the Oracle Streams pool to function properly. The current memory allocated to Oracle Streams pool by Automatic Shared Memory Management can be viewed by querying the V$SGA_DYNAMIC_COMPONENTS view.

See Also:

- Oracle Database PL/SQL Packages and Types Reference for more information about the max_sga_size apply parameter

- Oracle Database Administrator's Guide

- Oracle Database Reference

If Required, Specify Supplemental Logging at the Source Database

In an XStream configuration in which an inbound server applies changes captured by a capture process in an XStream Out configuration, supplemental logging might be required at the source database on columns in the tables for which an inbound server applies changes. The required supplemental logging depends on the configuration of the inbound server you create.

See Also:
"If Required, Configure Supplemental Logging"

Configuring XStream In

An inbound server in an XStream In configuration receives a stream of changes from a client application. The inbound server can apply these changes to database objects in an Oracle database, or it can process the changes in a customized way. A client application can attach to an inbound server and send row changes and DDL changes encapsulated in LCRs using the OCI or Java interface.

The CREATE_INBOUND procedure in the DBMS_XSTREAM_ADM package creates an inbound server. You must create the client application that communicates with the inbound server and sends LCRs to the inbound server.

Prerequisites

Before configuring XStream In, ensure that the following prerequisites are met:

- Complete the tasks described in "Preparing for XStream In".

Assumptions

This section makes the following assumptions:

- The name of the inbound server is xin.

- The inbound server applies all of the changes it receives from the XStream client application.

- The queue used by the inbound server is xstrmadmin.xin_queue.

Figure 9-1 provides an overview of this XStream In configuration.

Figure 9-1 Sample XStream In Configuration

To create an inbound server:

1. In SQL*Plus, connect to the database that will run the inbound server as the XStream administrator. See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.
If you are configuring XStream In in a CDB, then connect to the container to which the inbound server will apply changes. The container can be the root or a PDB. An inbound server can apply changes only in its own container. See Oracle Database Administrator's Guide for information about connecting to a container in a CDB in SQL*Plus. Also, see "XStream In and a Multitenant Environment" for information about using XStream In in a CDB.

2. Run the CREATE_INBOUND procedure.
For example, the following CREATE_INBOUND procedure configures an inbound server named xin:

BEGIN
DBMS_XSTREAM_ADM.CREATE_INBOUND(
server_name => 'xin',
queue_name  => 'xin_queue');
END;
/

Running this procedure performs the following actions:

- Creates an inbound server named xin.

- Sets the queue with the name xin_queue as the inbound server's queue, and creates this queue if it does not exist. This queue does not store LCRs sent by the client application. Instead, it stores error transactions if an LCR raises an error. The current user is the queue owner. In this example, the current user is the XStream administrator.

- Sets the current user as the apply user for the inbound server. In this example, the current user is the XStream administrator. The client application must connect to the database as the apply user to interact with the inbound server.

Tip:
By default, an inbound server does not use rules or rule sets. Therefore, it processes all LCRs sent to it by the client application. To add rules and rule sets, use the DBMS_XSTREAM_ADM package or the DBMS_RULE_ADM package. See Oracle Database PL/SQL Packages and Types Reference.

3. If necessary, create apply handlers for the inbound server.
Apply handlers are optional. Apply handlers process LCRs sent to an inbound server in a customized way.

See Also:
"LCR Processing Options for Inbound Servers"

4. Create and run the client application that will connect to the inbound server and send LCRs to it.
See Appendix A, "Sample XStream Client Application" for a sample application.

5. If the inbound server is disabled, then start the inbound server.
For example, enter the following:

exec DBMS_APPLY_ADM.START_APPLY('xin');

See Also:
Oracle Database PL/SQL Packages and Types Reference

10 Managing XStream In

This chapter provides instructions for managing XStream.

This chapter contains these topics:

- About Managing XStream In

- Starting an Inbound Server

- Stopping an Inbound Server

- Setting an Apply Parameter for an Inbound Server

- Changing the Apply User for an Inbound Server

- Managing Apply Errors

- Dropping Components in an XStream In Configuration

This chapter does not cover using rules, rule sets, or rule-based transformations with inbound servers. By default, an inbound server does not use rules or rule sets. Therefore, an inbound server applies all of the logical change records (LCRs) sent to it by an XStream client application. However, to filter the LCRs sent to an inbound server, you can add rules and rule sets to an inbound server using the DBMS_XSTREAM_ADM and DBMS_RULE_ADM packages. You can also specify rule-based transformations using the DBMS_XSTREAM_ADM package.

See Also:
Oracle Streams Concepts and Administration for information about using rules, rule sets, and rule-based transformations

About Managing XStream In

This chapter describes managing an XStream In configuration. This chapter provides instructions for modifying the database components that are part of an XStream In configuration, such as inbound servers.

The main interface for managing XStream In database components is PL/SQL. Specifically, use the following Oracle supplied PL/SQL packages to manage XStream In:

- DBMS_XSTREAM_ADM
The DBMS_XSTREAM_ADM package is the main package for managing XStream In. This package includes subprograms that enable you to configure, modify, or drop inbound servers. This package also enables you modify the rules, rule sets, and rule-based transformations used by inbound servers.

See Oracle Database PL/SQL Packages and Types Reference for detailed information about this package.

- DBMS_XSTREAM_AUTH
The DBMS_XSTREAM_AUTH package enables you to configure and modify XStream administrators.

See "Configure an XStream Administrator" for information about using this package to create an XStream administrator. See Oracle Database PL/SQL Packages and Types Reference for detailed information about this package.

- DBMS_APPLY_ADM
The DBMS_APPLY_ADM package enables you modify inbound servers.

See Oracle Database PL/SQL Packages and Types Reference for detailed information about this package.

See Also:

- Chapter 8, "XStream In Concepts"

- Chapter 9, "Configuring XStream In"

- Chapter 11, "Monitoring XStream In"

Starting an Inbound Server

A inbound server must be enabled for it to receive logical change records (LCRs) from an XStream client application and apply the LCRs. You run the START_APPLY procedure in the DBMS_APPLY_ADM package to start an existing inbound server.

To start an inbound server:

1. Connect to the inbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the START_APPLY procedure in the DBMS_APPLY_ADM package, and specify the inbound server for the apply_name parameter.

The following example starts a inbound server named xin.

Example 10-1 Starting an Outbound Server Named xout

BEGIN
DBMS_APPLY_ADM.START_APPLY(
apply_name => 'xin');
END;
/

See Also:
The Oracle Enterprise Manager Cloud Control online help for instructions about starting an apply process or an inbound server with Oracle Enterprise Manager Cloud Control

Stopping an Inbound Server

You run the STOP_APPLY procedure in the DBMS_APPLY_ADM package to stop an existing inbound server. You might stop an inbound server when you are troubleshooting a problem in an XStream configuration.

To stop an inbound server:

1. Connect to the inbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the STOP_APPLY procedure in the DBMS_APPLY_ADM package, and specify the inbound server for the apply_name parameter.

The following example stops a inbound server named xin.

Example 10-2 Stopping an Inbound Server Named xout

BEGIN
DBMS_APPLY_ADM.STOP_APPLY(
apply_name => 'xin');
END;
/

See Also:
The Oracle Enterprise Manager Cloud Control online help for instructions about stopping an apply process or an inbound server with Oracle Enterprise Manager Cloud Control

Setting an Apply Parameter for an Inbound Server

You set an apply parameter for an inbound server using the SET_PARAMETER procedure in the DBMS_XSTREAM_ADM package. Apply parameters control the way an inbound server operates.

To set an inbound server apply parameter:

1. Connect to the outbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the SET_PARAMETER procedure in the DBMS_XSTREAM_ADM package, and specify the following parameters:

- streams_name - Specify the name of the inbound server.

- streams_type - Specify apply.

- parameter - Specify the name of the apply parameter.

- value - Specify the value for the apply parameter.

The following example sets the parallelism parameter for an inbound server named xin to 4.

Example 10-3 Setting an Outbound Server Parameter

BEGIN
DBMS_XSTREAM_ADM.SET_PARAMETER(
streams_name => 'xin',
streams_type => 'apply'
parameter    => 'parallelism',
value        => '4');
END;
/

Note:

- The value parameter is always entered as a VARCHAR2 value, even if the parameter value is a number.

- If the value parameter is set to NULL or is not specified, then the parameter is set to its default value.

See Also:

- The Oracle Enterprise Manager Cloud Control online help for instructions about setting an apply parameter with Oracle Enterprise Manager Cloud Control

- Oracle Database PL/SQL Packages and Types Reference for information about apply parameters

Changing the Apply User for an Inbound Server

An inbound server applies LCRs in the security domain of its apply user, and the client application must attach to the inbound server as the apply user. This section describes changing the apply user for an inbound server using the ALTER_INBOUND procedure in the DBMS_XSTREAM_ADM package.

You can change the apply user when a client application must connect to an inbound server as a different user or when you want to apply changes using the privileges associated with a different user. Ensure that the apply user is granted the required privileges.

See Also:
Oracle Database PL/SQL Packages and Types Referencefor information about the privileges required by an apply user.

To change the apply user for an inbound server:

1. Connect to the inbound server database as the XStream administrator.
The XStream administrator must be granted the DBA role to change the apply user for an inbound server.

See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the ALTER_INBOUND procedure in the DBMS_XSTREAM_ADM package, and specify the following parameters:

- server_name - Specify the name of the inbound server.

- apply_user - Specify the new apply user.

Example 10-4 Changing the Apply User for an Inbound Server

To change the apply user to hr for an inbound server named xin, run the following procedure:

BEGIN
DBMS_XSTREAM_ADM.ALTER_INBOUND(
server_name => 'xin',
apply_user  => 'hr');
END;
/

See Also:

- "XStream In and Security"

- Oracle Database PL/SQL Packages and Types Reference

Managing Apply Errors

Apply errors result when an inbound server tries to apply an LCR, and an error is raised. When an apply error occurs, the LCR that caused the error and all of the other LCRs in the same transaction are moved to the error queue.

The following sections contain instructions for retrying and deleting apply errors:

- Retrying Apply Error Transactions

- Deleting Apply Error Transactions

- Managing Eager Errors Encountered by an Inbound Server

See Also:

- "The Error Queue for an Inbound Server"

- The Oracle Enterprise Manager Cloud Control online help for instructions on managing apply errors in Oracle Enterprise Manager Cloud Control

Retrying Apply Error Transactions

You can retry a specific error transaction, or you can retry all error transactions for an inbound server. You might need to make DML or DDL changes to database objects to correct the conditions that caused one or more apply errors before you retry error transactions.

This section contains these topics:

- Retrying a Specific Apply Error Transaction

- Retrying All Error Transactions for an Inbound Server

See Also:
Oracle Streams Replication Administrator's Guide for more information about setting tag values generated by the current session

Retrying a Specific Apply Error Transaction

When you retry an error transaction, you can execute it immediately or send the error transaction to a user procedure for modifications before executing it. The following sections provide instructions for each method:

- Retrying a Specific Apply Error Transaction Without a User Procedure

- Retrying a Specific Apply Error Transaction With a User Procedure

See Also:
Oracle Database PL/SQL Packages and Types Reference for more information about the EXECUTE_ERROR procedure

Retrying a Specific Apply Error Transaction Without a User Procedure

After you correct the conditions that caused an apply error, you can retry the transaction by running the EXECUTE_ERROR procedure in the DBMS_APPLY_ADM package without specifying a user procedure. In this case, the transaction is executed without any custom processing.

To retry a specific apply error transaction without a user procedure:

1. In SQL*Plus, connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the EXECUTE_ERROR procedure in the DBMS_APPLY_ADM package, and specify the transaction identifier.
To retry a transaction with the transaction identifier 5.4.312, run the following procedure:

BEGIN
DBMS_APPLY_ADM.EXECUTE_ERROR(
local_transaction_id => '5.4.312',
execute_as_user      => FALSE,
user_procedure       => NULL);
END;
/

If execute_as_user is TRUE, then the inbound server executes the transaction in the security context of the current user. If execute_as_user is FALSE, then the inbound server executes the transaction in the security context of the original receiver of the transaction. The original receiver is the user who was processing the transaction when the error was raised.

In either case, the user who executes the transaction must have privileges to perform DML and DDL changes on the apply objects and to run any apply handlers.

Retrying a Specific Apply Error Transaction With a User Procedure

You can retry an error transaction by running the EXECUTE_ERROR procedure in the DBMS_APPLY_ADM package and specify a user procedure to modify one or more LCRs in the transaction before the transaction is executed. The modifications should enable successful execution of the transaction.

For example, consider a case in which an apply error resulted because of a conflict. Examination of the error transaction reveals that the old value for the salary column in a row LCR contained the wrong value. Specifically, the current value of the salary of the employee with employee_id of 197 in the hr.employees table did not match the old value of the salary for this employee in the row LCR. Assume that the current value for this employee is 3250 in the hr.employees table. The example in this section creates a procedure to resolve the error.

To retry a specific apply error transaction with a user procedure:

1. In SQL*Plus, connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Given this scenario described previously, create the following user procedure to modify the salary in the row LCR that caused the error:

CREATE OR REPLACE PROCEDURE xstrmadmin.modify_emp_salary(
in_any                        IN      ANYDATA,
error_record                  IN      ALL_APPLY_ERROR%ROWTYPE,
error_message_number          IN      NUMBER,
messaging_default_processing  IN OUT  BOOLEAN,
out_any                       OUT     ANYDATA)
AS
row_lcr          SYS.LCR$_ROW_RECORD;
row_lcr_changed  BOOLEAN := FALSE;
res              NUMBER;
ob_owner         VARCHAR2(32);
ob_name          VARCHAR2(32);
cmd_type         VARCHAR2(30);
employee_id      NUMBER;
BEGIN
IF in_any.getTypeName() = 'SYS.LCR$_ROW_RECORD' THEN
-- Access the LCR
res := in_any.GETOBJECT(row_lcr);
-- Determine the owner of the database object for the LCR
ob_owner := row_lcr.GET_OBJECT_OWNER;
-- Determine the name of the database object for the LCR
ob_name := row_lcr.GET_OBJECT_NAME;
-- Determine the type of DML change
cmd_type := row_lcr.GET_COMMAND_TYPE;
IF (ob_owner = 'HR' AND ob_name = 'EMPLOYEES' AND cmd_type = 'UPDATE') THEN
-- Determine the employee_id of the row change
IF row_lcr.GET_VALUE('old', 'employee_id') IS NOT NULL THEN
employee_id := row_lcr.GET_VALUE('old', 'employee_id').ACCESSNUMBER();
IF (employee_id = 197) THEN
-- error_record.message_number should equal error_message_number
row_lcr.SET_VALUE(
value_type => 'OLD',
column_name => 'salary',
column_value => ANYDATA.ConvertNumber(3250));
row_lcr_changed := TRUE;
END IF;
END IF;
END IF;
END IF;
-- Specify that the inbound server continues to process the current message
messaging_default_processing := TRUE;
-- assign out_any appropriately
IF row_lcr_changed THEN
out_any := ANYDATA.ConvertObject(row_lcr);
ELSE
out_any := in_any;
END IF;
END;
/

3. Run the EXECUTE_ERROR procedure in the DBMS_APPLY_ADM package, and specify the transaction identifier and the user procedure.
To retry a transaction with the transaction identifier 5.6.924 and process the transaction with the modify_emp_salary procedure in the xstrmadmin schema before execution, run the following procedure:

BEGIN
DBMS_APPLY_ADM.EXECUTE_ERROR(
local_transaction_id => '5.6.924',
execute_as_user      => FALSE,
user_procedure       => 'xstrmadmin.modify_emp_salary');
END;
/

Note:
The user who runs the procedure must have SELECT privilege on ALL_APPLY_ERROR data dictionary view.

Retrying All Error Transactions for an Inbound Server

After you correct the conditions that caused all of the apply errors for an inbound server, you can retry all of the error transactions by running the EXECUTE_ALL_ERRORS procedure in the DBMS_APPLY_ADM package.

To retry all error transactions for an inbound server:

1. In SQL*Plus, connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the EXECUTE_ALL_ERRORS procedure in the DBMS_APPLY_ADM package, and specify the name of the inbound server.
To retry all of the error transactions for an inbound server named xin, run the following procedure:

BEGIN
DBMS_APPLY_ADM.EXECUTE_ALL_ERRORS(
apply_name       => 'xin',
execute_as_user  => FALSE);
END;
/

Note:
If you specify NULL for the apply_name parameter, and you have multiple inbound servers, then all of the apply errors are retried for all of the inbound servers.

Deleting Apply Error Transactions

You can delete a specific error transaction or you can delete all error transactions for an inbound server.

This section contains these topics:

- Deleting a Specific Apply Error Transaction

- Deleting All Error Transactions for an Inbound Server

Deleting a Specific Apply Error Transaction

If an error transaction should not be applied, then you can delete the transaction from the error queue using the DELETE_ERROR procedure in the DBMS_APPLY_ADM package.

To delete a specific apply error transaction:

1. In SQL*Plus, connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the DELETE_ERROR procedure in the DBMS_APPLY_ADM package, and specify the transaction identifier.
To delete a transaction with the transaction identifier 5.4.312, run the following procedure:

EXEC DBMS_APPLY_ADM.DELETE_ERROR(local_transaction_id => '5.4.312');

Deleting All Error Transactions for an Inbound Server

If none of the error transactions should be applied, then you can delete all of the error transactions by running the DELETE_ALL_ERRORS procedure in the DBMS_APPLY_ADM package.

To delete all error transactions for an inbound server:

1. In SQL*Plus, connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the DELETE_ALL_ERRORS procedure in the DBMS_APPLY_ADM package, and specify the name of the inbound server.
To delete all of the error transactions for an inbound server named xin, run the following procedure:

EXEC DBMS_APPLY_ADM.DELETE_ALL_ERRORS(apply_name => 'xin');

Note:
If you specify NULL for the apply_name parameter, and you have multiple inbound servers, then all of the apply errors are deleted for all of the inbound servers.

Managing Eager Errors Encountered by an Inbound Server

As a performance optimization, an inbound server can use eager apply to begin to apply large transactions before it receives the commit LCR. See "Optimizing XStream In Performance for Large Transactions" for information about eager apply.

An inbound server can encounter an error while eagerly applying a transaction. Because all of the LCRs are not available for the transaction, an EAGER ERROR is recorded for this failed transaction. In this case, an entry in the ALL_APPLY_ERROR view shows an eager error for the transaction, but the LCRs are not recorded in the error queue. If an error transaction is not an eager error transaction, then it is referred to as a normal error transaction.

Normal error transactions and eager error transactions must be managed differently. An inbound server moves a normal error transaction, including all of its LCRs, to the error queue, but an inbound server does not move an eager error transaction to the error queue.

An eager error causes the inbound server to stop. When it restarts, if the error queue has an EAGER ERROR for the restarting transaction, then the transaction is started as a normal transaction. That is, the LCRs in the large transaction spill to disk, and the inbound server begins to apply them only after the commit LCR is received.

The following statements apply to both normal error transactions and eager error transactions:

- The ALL_APPLY_ERROR and ALL_APPLY_ERROR_MESSAGES views contain information (metadata) about the error transaction.

- The inbound server does not apply the error transaction.

Table 10-1 explains the options for managing a normal error transaction.

Table 10-1 Options Available for Managing a Normal Error Transaction

Action

Mechanisms

Description

Delete the error transaction

DBMS_APPLY_ADM.DELETE_ERROR

DBMS_APPLY_ADM.DELETE_ALL_ERRORS

Oracle Enterprise Manager Cloud Control

The error transaction is deleted from the error queue, and the metadata about the error transaction is deleted. An inbound server does not try to reexecute the transaction when the inbound server is restarted. The transaction is not applied.

Execute the error transaction

DBMS_APPLY_ADM.EXECUTE_ERROR

DBMS_APPLY_ADM.EXECUTE_ALL_ERRORS

Oracle Enterprise Manager Cloud Control

The error transaction in the error queue is executed. If there are no errors during execution, then the transaction is applied. If an LCR raises an error during execution, then the normal error transaction is moved back to the error queue.

Retain the error transaction

None. (The error transaction is retained automatically.)

The error transaction remains in the error queue even if the inbound server is restarted. The metadata about the error transaction is also retained. The transaction is not applied.

Table 10-2 explains the options for managing an eager error transaction.

Table 10-2 Options Available for Managing an Eager Error Transaction

Action

Mechanisms

Description

Delete error transaction

DBMS_APPLY_ADM.DELETE_ERROR

DBMS_APPLY_ADM.DELETE_ALL_ERRORS

Oracle Enterprise Manager Cloud Control

The metadata about the eager error transaction is deleted. When the inbound server is restarted, it attempts to execute the transaction as an eager transaction. If the inbound server does not encounter an error during execution, then the transaction is applied successfully. If the inbound server encounters an error during execution, then the eager error transaction is recorded.

Retain error transaction

None. (The metadata about the error transaction is retained automatically.)

The metadata about the eager error transaction is retained. When the inbound server is restarted, it attempts to execute the transaction as a normal transaction.

Specifically, the inbound server spills the transaction to disk and attempts to execute the transaction. If the inbound server does not encounter an error during execution, then the transaction is applied successfully. If the inbound server encounters an error during execution, then the transaction becomes a normal error transaction. In this case, the LCR that raised the error and all of the other LCRs in the transaction are moved to the error queue. After the normal error transaction is moved to the error queue, you must manage the error transaction as a normal error transaction (not an eager error transaction).

Note:
If you attempt to execute an eager error transaction manually using the DBMS_APPLY_ADM package or Oracle Enterprise Manager Cloud Control, then the following error is raised:

ORA-26909: cannot reexecute an eager error

An eager error transaction cannot be executed manually. Instead, it is executed automatically when the inbound server is enabled.

To manage an eager error transaction encountered by an inbound server:

1. Connect to the inbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Query the ERROR_TYPE column in the ALL_APPLY_ERROR data dictionary view:

SELECT APPLY_NAME, ERROR_TYPE FROM ALL_APPLY_ERROR;

Follow the appropriate instructions based on the error type:

- If the ERROR_TYPE column shows EAGER ERROR, then proceed to Step 3.

- If the ERROR_TYPE column shows NULL, then the apply error is not an eager error, and you cannot use the instructions in this section to manage it. Instead, use the instructions in "Retrying Apply Error Transactions" and "Deleting Apply Error Transactions".

3. Examine the error message raised by the LCR, and determine the cause of the error.

See "Checking for Apply Errors" and "Displaying Detailed Information About Apply Errors" for information about checking for apply errors using data dictionary views.

See Oracle Enterprise Manager Cloud Control online help for information about checking for apply errors using Oracle Enterprise Manager Cloud Control.

4. If possible, determine how to avoid the error, and make any changes necessary to avoid the error.
See Chapter 12, "Troubleshooting XStream In" for information about common apply errors and solutions for them.

5. Either retain the error transaction or delete the error transaction:

- Delete the error transaction only if you have corrected the problem. The inbound server reexecutes the transaction when it is enabled.
For example, to delete a transaction with the transaction identifier 5.4.312, run the following procedure:

EXEC DBMS_APPLY_ADM.DELETE_ERROR(local_transaction_id => '5.4.312');

- Retain the error transaction if you cannot correct the problem now or if you plan to reexecute it in the future. No action is necessary to retain the error transaction. It remains in the error queue until it is reexecuted or deleted.

See Table 10-2 for more information about these choices.

Caution:
It might not be possible to recover a normal error transaction that is deleted. Before deleting the error transaction, ensure that the error type is EAGER ERROR.

See "Deleting Apply Error Transactions" for more information about deleting an error transaction using the DBMS_APPLY_ADM package.

See the Oracle Enterprise Manager Cloud Control online help for information about deleting an error transaction using Oracle Enterprise Manager Cloud Control.

6. If the inbound server is disabled, then start the inbound server.
Query the STATUS column in the ALL_APPLY_ERROR view to determine whether the inbound server is enabled or disabled.

If the disable_on_error apply parameter is set to Y for the inbound server, then the inbound server becomes disabled when it encounters the error and remains disabled.

If the disable_on_error apply parameter is set to N for the inbound server, then the inbound server stops and restarts automatically when it encounters the error.

See Table 10-2 for information about how the inbound server handles the error transaction based on your choice in Step 5.

See "Starting an Inbound Server" for information about starting an inbound server or apply process using the DBMS_APPLY_ADM package.

See the Oracle Enterprise Manager Cloud Control online help for information about starting an inbound server or apply process using Oracle Enterprise Manager Cloud Control.

Note:
If you have both purchased a license for the Oracle GoldenGate product and have enabled the XStream optimizations for Oracle Streams by running the DBMS_XSTREAM_ADM.ENABLE_GG_XSTREAM_FOR_STREAMS procedure, then an apply process in an Oracle Streams configuration can encounter errors of the EAGER ERROR type. Use the instructions in this section to manage eager apply process errors. When the XStream optimizations for Oracle Streams are not enabled, apply processes cannot encounter eager errors.

See Also:

- Oracle Database Reference

- Oracle Database PL/SQL Packages and Types Reference

Dropping Components in an XStream In Configuration

This section describes dropping an inbound server using the DROP_INBOUND procedure in the DBMS_XSTREAM_ADM package.

This procedure always drops the specified inbound server. This procedure also drops the queue for the inbound server if both of the following conditions are met:

- One call to the CREATE_INBOUND procedure created the inbound server and the queue.

- The inbound server is the only subscriber to the queue.

If either one of the preceding conditions is not met, then the DROP_INBOUND procedure only drops the inbound server. It does not drop the queue.

To drop an inbound server:

1. Connect to the inbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the DROP_INBOUND procedure.

Example 10-5 Dropping an Inbound Server

To drop an inbound server named xin, run the following procedure:

exec DBMS_XSTREAM_ADM.DROP_INBOUND('xin');

If the inbound server's queue is not dropped automatically, then run the REMOVE_QUEUE procedure to drop it.

Example 10-6 Dropping an Inbound Server's Queue

To drop a queue named xin_queue, run the following procedure:

exec DBMS_XSTREAM_ADM.REMOVE_QUEUE('xin_queue');

See Also:
Oracle Database PL/SQL Packages and Types Reference

11 Monitoring XStream In

This chapter provides instructions for monitoring XStream.

This chapter contains these topics:

- Displaying Session Information for Inbound Servers

- Displaying General Information About an Inbound Server

- Displaying the Status and Error Information for an Inbound Server

- Displaying Apply Parameter Settings for an Inbound Server

- Displaying the Position Information for an Inbound Server

- Checking for Apply Errors

- Displaying Detailed Information About Apply Errors

With XStream In, an Oracle Streams apply process functions as an inbound server. Therefore, you can also use the data dictionary views for apply processes to monitor inbound servers.

Note:
Whenever possible, this chapter uses ALL_ static data dictionary views for query examples. In some cases, information in the ALL_ views is more limited than the information in the DBA_ views.
In SQL*Plus, trusted XStream administrators can query the ALL_ and DBA_ views. Untrusted XStream administrators can query the ALL_ views only.

See Also:

- Chapter 3, "XStream Out Concepts"

- "XStream Use Cases"

- Chapter 4, "Configuring XStream Out"

- Chapter 12, "Troubleshooting XStream In"

- Oracle Streams Concepts and Administration

Displaying Session Information for Inbound Servers

The query in this section displays the following session information about each XStream component in a database:

- The XStream component name

- The session identifier

- The serial number

- The operating system process identification number

- The XStream process number

This query is especially useful for determining the session information for specific XStream components when there are multiple XStream In components configured in a database.

To display this information for each XStream component in a database:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN ACTION HEADING 'XStream Component' FORMAT A30
COLUMN SID HEADING 'Session ID' FORMAT 99999
COLUMN SERIAL# HEADING 'Session|Serial|Number' FORMAT 99999999
COLUMN PROCESS HEADING 'Operating System|Process Number' FORMAT A17
COLUMN PROCESS_NAME HEADING 'XStream|Process|Number' FORMAT A7

SELECT /*+PARAM('_module_action_old_length',0)*/ ACTION,
SID,
SERIAL#,
PROCESS,
SUBSTR(PROGRAM,INSTR(PROGRAM,'(')+1,4) PROCESS_NAME
FROM V$SESSION
WHERE MODULE ='XStream';

Your output for an XStream In configuration looks similar to the following:

Session                   XStream
Serial Operating System  Process
XStream Component              Session ID    Number Process Number    Number
------------------------------ ---------- --------- ----------------- -------
XIN - Apply Reader                     19         9 27304             AS01
XIN - Apply Server                     22         5 27308             AS03
XIN - Apply Server                     25        31 27313             AS05
XIN - Apply Coordinator               112         7 27302             AP01
XIN - Apply Server                    113         5 27306             AS02
XIN - Propagation Receiver            114        17 27342             TNS
XIN - Apply Server                    115        39 27311             AS04

The row that shows TNS for the XStream process number contains information about the session for the XStream client application that is attached to the inbound server.

Note:
To run this query, a user must have the necessary privileges to query the V$SESSION view.

See Also:
Oracle Database Reference for more information about the V$SESSION view

Displaying General Information About an Inbound Server

You can display the following information for an inbound server by running the query in this section:

- The inbound server name

- The owner of the queue used by the inbound server

- The name of the queue used by the inbound server

- The apply user for the inbound server

To display general information about an inbound server:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN SERVER_NAME HEADING 'Inbound Server Name' FORMAT A20
COLUMN QUEUE_OWNER HEADING 'Queue Owner' FORMAT A15
COLUMN QUEUE_NAME HEADING 'Queue Name' FORMAT A15
COLUMN APPLY_USER HEADING 'Apply User' FORMAT A15

SELECT SERVER_NAME,
QUEUE_OWNER,
QUEUE_NAME,
APPLY_USER
FROM ALL_XSTREAM_INBOUND;

Your output looks similar to the following:

Inbound Server Name  Queue Owner     Queue Name      Apply User
-------------------- --------------- --------------- ---------------
XIN                  XSTRMADMIN      XIN_QUEUE       XSTRMADMIN

See Also:
Oracle Database Reference

Displaying the Status and Error Information for an Inbound Server

The DBA_APPLY view shows XStream In in the PURPOSE column for an apply process that is functioning as an inbound server.

To display the status of an inbound server:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN APPLY_NAME HEADING 'Inbound Server|Name' FORMAT A15
COLUMN STATUS HEADING 'Status' FORMAT A8
COLUMN ERROR_NUMBER HEADING 'Error Number' FORMAT 9999999
COLUMN ERROR_MESSAGE HEADING 'Error Message' FORMAT A40

SELECT APPLY_NAME,
STATUS,
ERROR_NUMBER,
ERROR_MESSAGE
FROM DBA_APPLY
WHERE PURPOSE = 'XStream In';

Your output looks similar to the following:

Inbound Server
Name            Status   Error Number Error Message
--------------- -------- ------------ ----------------------------------------
XIN             ENABLED

This output shows that XIN is an apply process that is functioning as an inbound server.

Note:
This example queries the DBA_APPLY view. This view enables trusted users to see information for all apply users in the database. Untrusted users must query the ALL_APPLY view, which limits information to the current user.

See Also:
Oracle Database Reference

Displaying Apply Parameter Settings for an Inbound Server

Apply parameters determine how an inbound server operates.

To display the apply parameter settings for an inbound server:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN APPLY_NAME HEADING 'Inbound Server|Name' FORMAT A15
COLUMN PARAMETER HEADING 'Parameter' FORMAT A30
COLUMN VALUE HEADING 'Value' FORMAT A22
COLUMN SET_BY_USER HEADING 'Set by|User?' FORMAT A10

SELECT APPLY_NAME,
PARAMETER,
VALUE,
SET_BY_USER
FROM ALL_APPLY_PARAMETERS a, ALL_XSTREAM_INBOUND i
WHERE a.APPLY_NAME=i.SERVER_NAME
ORDER BY a.PARAMETER;

Your output looks similar to the following:

Inbound Server                                                        Set by
Name            Parameter                      Value                  User?
--------------- ------------------------------ ---------------------- ----------
XIN             ALLOW_DUPLICATE_ROWS           N                      NO
XIN             APPLY_SEQUENCE_NEXTVAL         Y                      NO
XIN             COMMIT_SERIALIZATION           DEPENDENT_TRANSACTIONS NO
XIN             COMPARE_KEY_ONLY               Y                      NO
XIN             COMPUTE_LCR_DEP_ON_ARRIVAL     N                      NO
XIN             DISABLE_ON_ERROR               Y                      NO
XIN             DISABLE_ON_LIMIT               N                      NO
XIN             EAGER_SIZE                     9500                   NO
XIN             ENABLE_XSTREAM_TABLE_STATS     Y                      NO
XIN             EXCLUDETAG                                            NO
XIN             EXCLUDETRANS                                          NO
XIN             EXCLUDEUSER                                           NO
XIN             EXCLUDEUSERID                                         NO
XIN             GETAPPLOPS                     Y                      NO
XIN             GETREPLICATES                  N                      NO
XIN             GROUPTRANSOPS                  250                    NO
XIN             HANDLECOLLISIONS               N                      NO
XIN             IGNORE_TRANSACTION                                    NO
XIN             MAXIMUM_SCN                    INFINITE               NO
XIN             MAX_PARALLELISM                50                     NO
XIN             MAX_SGA_SIZE                   INFINITE               NO
XIN             OPTIMIZE_PROGRESS_TABLE        Y                      NO
XIN             OPTIMIZE_SELF_UPDATES          Y                      NO
XIN             PARALLELISM                    4                      NO
XIN             PRESERVE_ENCRYPTION            Y                      NO
XIN             RTRIM_ON_IMPLICIT_CONVERSION   Y                      NO
XIN             STARTUP_SECONDS                0                      NO
XIN             SUPPRESSTRIGGERS               Y                      NO
XIN             TIME_LIMIT                     INFINITE               NO
XIN             TRACE_LEVEL                    0                      NO
XIN             TRANSACTION_LIMIT              INFINITE               NO
XIN             TXN_AGE_SPILL_THRESHOLD        900                    NO
XIN             TXN_LCR_SPILL_THRESHOLD        10000                  NO
XIN             WRITE_ALERT_LOG                Y                      NO

Inbound servers ignore some apply parameter settings. See Oracle Database PL/SQL Packages and Types Reference for information about these apply parameters.

Note:
If the Set by User? column is NO for a parameter, then the parameter is set to its default value. If the Set by User? column is YES for a parameter, then the parameter was set by a user and might or might not be set to its default value.

See Also:

- "Setting an Apply Parameter for an Inbound Server"

- Oracle Database PL/SQL Packages and Types Reference for information about apply parameters

Displaying the Position Information for an Inbound Server

For an inbound server, you can view position information by querying the ALL_XSTREAM_INBOUND_PROGRESS view. Specifically, you can display the following position information by running the query in this section:

- The inbound server name

- The applied low position for the inbound server

- The spill position for the inbound server

- The applied high position for the inbound server

- The processed low position for the inbound server

To display the position information for an inbound server:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN SERVER_NAME HEADING 'Inbound|Server|Name' FORMAT A10
COLUMN APPLIED_LOW_POSITION HEADING 'Applied Low|Position' FORMAT A15
COLUMN SPILL_POSITION HEADING 'Spill Position' FORMAT A15
COLUMN APPLIED_HIGH_POSITION HEADING 'Applied High|Position' FORMAT A15
COLUMN PROCESSED_LOW_POSITION HEADING 'Processed Low|Position' FORMAT A15

SELECT SERVER_NAME,
APPLIED_LOW_POSITION,
SPILL_POSITION,
APPLIED_HIGH_POSITION,
PROCESSED_LOW_POSITION
FROM ALL_XSTREAM_INBOUND_PROGRESS;

Your output looks similar to the following:

Inbound
Server     Applied Low                     Applied High    Processed Low
Name       Position        Spill Position  Position        Position
---------- --------------- --------------- --------------- ---------------
XIN        C10A            C11D            C10A            C11D

The values of the positions shown in the output were set by the client application that attaches to the inbound server. However, the inbound server determines which values are the current applied low position, spill position, applied high position, and processed low position.

See Also:

- Oracle Database Reference

- "Position Order in an LCR Stream"

- "Position of LCRs and XStream In"

Checking for Apply Errors

Trusted users can check for apply errors by querying the DBA_APPLY_ERROR data dictionary view or by using Oracle Enterprise Manager Cloud Control. Untrusted users can check for apply errors by querying the ALL_APPLY_ERROR data dictionary view.

To check for apply errors:

1. Connect to the database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

COLUMN APPLY_NAME HEADING 'Inbound|Server|Name' FORMAT A7
COLUMN SOURCE_DATABASE HEADING 'Source|Database' FORMAT A8
COLUMN SOURCE_TRANSACTION_ID HEADING 'Source|Transaction|ID' FORMAT A11
COLUMN MESSAGE_NUMBER HEADING 'Failed Message|in Error|Transaction' FORMAT 99999999
COLUMN ERROR_NUMBER HEADING 'Error Number' FORMAT 99999999
COLUMN ERROR_MESSAGE HEADING 'Error Message' FORMAT A10
COLUMN MESSAGE_COUNT HEADING 'Messages in|Error|Transaction' FORMAT 99999999

SELECT APPLY_NAME,
SOURCE_DATABASE,
SOURCE_TRANSACTION_ID,
MESSAGE_NUMBER,
ERROR_NUMBER,
ERROR_MESSAGE,
MESSAGE_COUNT
FROM ALL_APPLY_ERROR;

Note:
Trusted users should replace ALL_APPLY_ERROR with DBA_APPLY_ERROR in the query.

If there are any apply errors, then your output looks similar to the following:

Inbound          Source      Failed Message                         Messages in
Server  Source   Transaction       in Error                               Error
Name    Database ID             Transaction Error Number Error Mess Transaction
------- -------- ----------- -------------- ------------ ---------- -----------
XIN     OUTX.EXA 19.20.215                1         1031 ORA-01031:           1
MPLE.COM                                          insuffici
ent privil
eges
XIN     OUTX.EXA 11.21.158                1         1031 ORA-01031:           1
MPLE.COM                                          insuffici
ent privil
eges

If there are apply errors, then you can either try to reexecute the transactions that encountered the errors, or you can delete the transactions. If you want to reexecute a transaction that encountered an error, then first correct the condition that caused the transaction to raise an error.

If you want to delete a transaction that encountered an error, then you might need to resynchronize data manually if you are sharing data between multiple databases. Remember to set an appropriate session tag, if necessary, when you resynchronize data manually.

See Also:

- "The Error Queue for an Inbound Server"

- "Managing Apply Errors"

Displaying Detailed Information About Apply Errors

This section contains SQL scripts that you can use to display detailed information about the error transactions in the error queue in a database.

To use these scripts, complete the following steps:

1. Step 1: Grant Explicit SELECT Privilege on the ALL_APPLY_ERROR View

2. Step 2: Create a Procedure that Prints the Value in an ANYDATA Object

3. Step 3: Create a Procedure that Prints a Specified LCR

4. Step 4: Create a Procedure that Prints All the LCRs in the Error Queue

5. Step 5: Create a Procedure that Prints All the Error LCRs for a Transaction

See Also:

- "The Error Queue for an Inbound Server"

- "Managing Apply Errors"

Step 1: Grant Explicit SELECT Privilege on the ALL_APPLY_ERROR View

The user who creates and runs the print_errors and print_transaction procedures described in the following sections must be granted explicit SELECT privilege on the ALL_APPLY_ERROR data dictionary view. This privilege cannot be granted through a role. Running the GRANT_ADMIN_PRIVILEGE procedure in the DBMS_XSTREAM_AUTH package on a user grants this privilege to the user.

To grant explicit SELECT privilege on the ALL_APPLY_ERROR view:

1. In SQL*Plus, connect as an administrative user who can grant privileges.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Grant SELECT privilege on the ALL_APPLY_ERROR data dictionary view to the appropriate user. For example, to grant this privilege to the xstrmadmin user, run the following statement:

GRANT SELECT ON ALL_APPLY_ERROR TO xstrmadmin;

3. Grant EXECUTE privilege on the DBMS_APPLY_ADM package. For example, to grant this privilege to the xstrmadmin user, run the following statement:

GRANT EXECUTE ON DBMS_APPLY_ADM TO xstrmadmin;

4. Connect to the database as the user to whom you granted the privilege in Step 2 and 3.

Step 2: Create a Procedure that Prints the Value in an ANYDATA Object

The following procedure prints the value in a specified ANYDATA object for some selected data types. Optionally, you can add more data types to this procedure.

CREATE OR REPLACE PROCEDURE print_any(data IN ANYDATA) IS
tn  VARCHAR2(61);
str VARCHAR2(4000);
chr VARCHAR2(1000);
num NUMBER;
dat DATE;
rw  RAW(4000);
res NUMBER;
BEGIN
IF data IS NULL THEN
DBMS_OUTPUT.PUT_LINE('NULL value');
RETURN;
END IF;
tn := data.GETTYPENAME();
IF tn = 'SYS.VARCHAR2' THEN
res := data.GETVARCHAR2(str);
DBMS_OUTPUT.PUT_LINE(SUBSTR(str,0,253));
ELSIF tn = 'SYS.CHAR' then
res := data.GETCHAR(chr);
DBMS_OUTPUT.PUT_LINE(SUBSTR(chr,0,253));
ELSIF tn = 'SYS.VARCHAR' THEN
res := data.GETVARCHAR(chr);
DBMS_OUTPUT.PUT_LINE(chr);
ELSIF tn = 'SYS.NUMBER' THEN
res := data.GETNUMBER(num);
DBMS_OUTPUT.PUT_LINE(num);
ELSIF tn = 'SYS.DATE' THEN
res := data.GETDATE(dat);
DBMS_OUTPUT.PUT_LINE(dat);
ELSIF tn= 'SYS.TIMESTAMP' THEN
res := data.GETTIMESTAMP(dat);
DBMS_OUTPUT.PUT_LINE(TO_CHAR(dat,'DD-MON-RR HH.MI.SSXFF AM'));
ELSIF tn= 'SYS.TIMESTAMPTZ' THEN
res := data.GETTIMESTAMPTZ(dat);
DBMS_OUTPUT.PUT_LINE(TO_CHAR(dat,'DD-MON-RR HH.MI.SSXFF AM'));
ELSIF tn= 'SYS.TIMESTAMPLTZ' THEN
res := data.GETTIMESTAMPLTZ(dat);
DBMS_OUTPUT.PUT_LINE(TO_CHAR(dat,'DD-MON-RR HH.MI.SSXFF AM'));
ELSIF tn = 'SYS.RAW' THEN
-- res := data.GETRAW(rw);
-- DBMS_OUTPUT.PUT_LINE(SUBSTR(DBMS_LOB.SUBSTR(rw),0,253));
DBMS_OUTPUT.PUT_LINE('BLOB Value');
ELSIF tn = 'SYS.BLOB' THEN
DBMS_OUTPUT.PUT_LINE('BLOB Found');
ELSE
DBMS_OUTPUT.PUT_LINE('typename is ' || tn);
END IF;
END print_any;
/

Step 3: Create a Procedure that Prints a Specified LCR

The following procedure prints a specified LCR. It calls the print_any procedure created in "Step 2: Create a Procedure that Prints the Value in an ANYDATA Object".

CREATE OR REPLACE PROCEDURE print_lcr(lcr IN ANYDATA) IS
typenm    VARCHAR2(61);
ddllcr    SYS.LCR$_DDL_RECORD;
proclcr   SYS.LCR$_PROCEDURE_RECORD;
rowlcr    SYS.LCR$_ROW_RECORD;
res       NUMBER;
newlist   SYS.LCR$_ROW_LIST;
oldlist   SYS.LCR$_ROW_LIST;
ddl_text  CLOB;
ext_attr  ANYDATA;
BEGIN
typenm := lcr.GETTYPENAME();
DBMS_OUTPUT.PUT_LINE('type name: ' || typenm);
IF (typenm = 'SYS.LCR$_DDL_RECORD') THEN
res := lcr.GETOBJECT(ddllcr);
DBMS_OUTPUT.PUT_LINE('source database: ' ||
ddllcr.GET_SOURCE_DATABASE_NAME);
DBMS_OUTPUT.PUT_LINE('owner: ' || ddllcr.GET_OBJECT_OWNER);
DBMS_OUTPUT.PUT_LINE('object: ' || ddllcr.GET_OBJECT_NAME);
DBMS_OUTPUT.PUT_LINE('is tag null: ' || ddllcr.IS_NULL_TAG);
DBMS_LOB.CREATETEMPORARY(ddl_text, TRUE);
ddllcr.GET_DDL_TEXT(ddl_text);
DBMS_OUTPUT.PUT_LINE('ddl: ' || ddl_text);
-- Print extra attributes in DDL LCR
ext_attr := ddllcr.GET_EXTRA_ATTRIBUTE('serial#');
IF (ext_attr IS NOT NULL) THEN
DBMS_OUTPUT.PUT_LINE('serial#: ' || ext_attr.ACCESSNUMBER());
END IF;
ext_attr := ddllcr.GET_EXTRA_ATTRIBUTE('session#');
IF (ext_attr IS NOT NULL) THEN
DBMS_OUTPUT.PUT_LINE('session#: ' || ext_attr.ACCESSNUMBER());
END IF;
ext_attr := ddllcr.GET_EXTRA_ATTRIBUTE('thread#');
IF (ext_attr IS NOT NULL) THEN
DBMS_OUTPUT.PUT_LINE('thread#: ' || ext_attr.ACCESSNUMBER());
END IF;
ext_attr := ddllcr.GET_EXTRA_ATTRIBUTE('tx_name');
IF (ext_attr IS NOT NULL) THEN
DBMS_OUTPUT.PUT_LINE('transaction name: ' || ext_attr.ACCESSVARCHAR2());
END IF;
ext_attr := ddllcr.GET_EXTRA_ATTRIBUTE('username');
IF (ext_attr IS NOT NULL) THEN
DBMS_OUTPUT.PUT_LINE('username: ' || ext_attr.ACCESSVARCHAR2());
END IF;
DBMS_LOB.FREETEMPORARY(ddl_text);
ELSIF (typenm = 'SYS.LCR$_ROW_RECORD') THEN
res := lcr.GETOBJECT(rowlcr);
DBMS_OUTPUT.PUT_LINE('source database: ' ||
rowlcr.GET_SOURCE_DATABASE_NAME);
DBMS_OUTPUT.PUT_LINE('owner: ' || rowlcr.GET_OBJECT_OWNER);
DBMS_OUTPUT.PUT_LINE('object: ' || rowlcr.GET_OBJECT_NAME);
DBMS_OUTPUT.PUT_LINE('is tag null: ' || rowlcr.IS_NULL_TAG);
DBMS_OUTPUT.PUT_LINE('command_type: ' || rowlcr.GET_COMMAND_TYPE);
oldlist := rowlcr.GET_VALUES('old');
FOR i IN 1..oldlist.COUNT LOOP
IF oldlist(i) IS NOT NULL THEN
DBMS_OUTPUT.PUT_LINE('old(' || i || '): ' || oldlist(i).column_name);
print_any(oldlist(i).data);
END IF;
END LOOP;
newlist := rowlcr.GET_VALUES('new', 'n');
FOR i in 1..newlist.count LOOP
IF newlist(i) IS NOT NULL THEN
DBMS_OUTPUT.PUT_LINE('new(' || i || '): ' || newlist(i).column_name);
print_any(newlist(i).data);
END IF;
END LOOP;
-- Print extra attributes in row LCR
ext_attr := rowlcr.GET_EXTRA_ATTRIBUTE('row_id');
IF (ext_attr IS NOT NULL) THEN
DBMS_OUTPUT.PUT_LINE('row_id: ' || ext_attr.ACCESSUROWID());
END IF;
ext_attr := rowlcr.GET_EXTRA_ATTRIBUTE('serial#');
IF (ext_attr IS NOT NULL) THEN
DBMS_OUTPUT.PUT_LINE('serial#: ' || ext_attr.ACCESSNUMBER());
END IF;
ext_attr := rowlcr.GET_EXTRA_ATTRIBUTE('session#');
IF (ext_attr IS NOT NULL) THEN
DBMS_OUTPUT.PUT_LINE('session#: ' || ext_attr.ACCESSNUMBER());
END IF;
ext_attr := rowlcr.GET_EXTRA_ATTRIBUTE('thread#');
IF (ext_attr IS NOT NULL) THEN
DBMS_OUTPUT.PUT_LINE('thread#: ' || ext_attr.ACCESSNUMBER());
END IF;
ext_attr := rowlcr.GET_EXTRA_ATTRIBUTE('tx_name');
IF (ext_attr IS NOT NULL) THEN
DBMS_OUTPUT.PUT_LINE('transaction name: ' || ext_attr.ACCESSVARCHAR2());
END IF;
ext_attr := rowlcr.GET_EXTRA_ATTRIBUTE('username');
IF (ext_attr IS NOT NULL) THEN
DBMS_OUTPUT.PUT_LINE('username: ' || ext_attr.ACCESSVARCHAR2());
END IF;
ELSE
DBMS_OUTPUT.PUT_LINE('Non-LCR Message with type ' || typenm);
END IF;
END print_lcr;
/

Step 4: Create a Procedure that Prints All the LCRs in the Error Queue

The following procedure prints all of the LCRs in all of the error queues. It calls the print_lcr procedure created in "Step 3: Create a Procedure that Prints a Specified LCR".

CREATE OR REPLACE PROCEDURE print_errors IS
CURSOR c IS
SELECT LOCAL_TRANSACTION_ID,
SOURCE_DATABASE,
MESSAGE_NUMBER,
MESSAGE_COUNT,
ERROR_NUMBER,
ERROR_MESSAGE
FROM ALL_APPLY_ERROR
ORDER BY SOURCE_DATABASE, SOURCE_COMMIT_SCN;
i      NUMBER;
txnid  VARCHAR2(30);
source VARCHAR2(128);
msgno  NUMBER;
msgcnt NUMBER;
errnum NUMBER := 0;
errno  NUMBER;
errmsg VARCHAR2(2000);
lcr    ANYDATA;
r      NUMBER;
BEGIN
FOR r IN c LOOP
errnum := errnum + 1;
msgcnt := r.MESSAGE_COUNT;
txnid  := r.LOCAL_TRANSACTION_ID;
source := r.SOURCE_DATABASE;
msgno  := r.MESSAGE_NUMBER;
errno  := r.ERROR_NUMBER;
errmsg := r.ERROR_MESSAGE;
DBMS_OUTPUT.PUT_LINE('*************************************************');
DBMS_OUTPUT.PUT_LINE('----- ERROR #' || errnum);
DBMS_OUTPUT.PUT_LINE('----- Local Transaction ID: ' || txnid);
DBMS_OUTPUT.PUT_LINE('----- Source Database: ' || source);
DBMS_OUTPUT.PUT_LINE('----Error in Message: '|| msgno);
DBMS_OUTPUT.PUT_LINE('----Error Number: '||errno);
DBMS_OUTPUT.PUT_LINE('----Message Text: '||errmsg);
FOR i IN 1..msgcnt LOOP
DBMS_OUTPUT.PUT_LINE('--message: ' || i);
lcr := DBMS_APPLY_ADM.GET_ERROR_MESSAGE(i, txnid);
print_lcr(lcr);
END LOOP;
END LOOP;
END print_errors;
/

To run this procedure after you create it, enter the following:

SET SERVEROUTPUT ON SIZE 1000000

EXEC print_errors

Step 5: Create a Procedure that Prints All the Error LCRs for a Transaction

The following procedure prints all the LCRs in the error queue for a particular transaction. It calls the print_lcr procedure created in "Step 3: Create a Procedure that Prints a Specified LCR".

CREATE OR REPLACE PROCEDURE print_transaction(ltxnid IN VARCHAR2) IS
i      NUMBER;
txnid  VARCHAR2(30);
source VARCHAR2(128);
msgno  NUMBER;
msgcnt NUMBER;
errno  NUMBER;
errmsg VARCHAR2(2000);
lcr    ANYDATA;
BEGIN
SELECT LOCAL_TRANSACTION_ID,
SOURCE_DATABASE,
MESSAGE_NUMBER,
MESSAGE_COUNT,
ERROR_NUMBER,
ERROR_MESSAGE
INTO txnid, source, msgno, msgcnt, errno, errmsg
FROM ALL_APPLY_ERROR
WHERE LOCAL_TRANSACTION_ID =  ltxnid;
DBMS_OUTPUT.PUT_LINE('----- Local Transaction ID: ' || txnid);
DBMS_OUTPUT.PUT_LINE('----- Source Database: ' || source);
DBMS_OUTPUT.PUT_LINE('----Error in Message: '|| msgno);
DBMS_OUTPUT.PUT_LINE('----Error Number: '||errno);
DBMS_OUTPUT.PUT_LINE('----Message Text: '||errmsg);
FOR i IN 1..msgcnt LOOP
DBMS_OUTPUT.PUT_LINE('--message: ' || i);
lcr := DBMS_APPLY_ADM.GET_ERROR_MESSAGE(i, txnid); -- gets the LCR
print_lcr(lcr);
END LOOP;
END print_transaction;
/

To run this procedure after you create it, pass to it the local transaction identifier of an error transaction. For example, if the local transaction identifier is 1.17.2485, then enter the following:

SET SERVEROUTPUT ON SIZE 1000000

EXEC print_transaction('1.17.2485')

12 Troubleshooting XStream In

This chapter describes common problems you might encounter while using XStream and explains how to solve them.

This chapter contains the following topics:

- Diagnosing Problems with XStream In

- Problems and Solutions for XStream In

- How to Get More Help with XStream In

See Also:

- Chapter 3, "XStream Out Concepts"

- "XStream Use Cases"

- Chapter 4, "Configuring XStream Out"

Diagnosing Problems with XStream In

To diagnose problems with XStream In, use the techniques described in this section.

This section contains these topics:

- Viewing Alerts

- Checking the Trace File and Alert Log for Problems

Viewing Alerts

An alert is a warning about a potential problem or an indication that a critical threshold has been crossed. There are two types of alerts:

- Stateless: Alerts that indicate single events that are not necessarily tied to the system state. For example, an alert that indicates that a capture aborted with a specific error is a stateless alert.

- Stateful: Alerts that are associated with a specific system state. Stateful alerts are usually based on a numeric value, with thresholds defined at warning and critical levels. For example, an alert on the current Streams pool memory usage percentage, with the warning level at 85% and the critical level at 95%, is a stateful alert.

An Oracle database generates a stateless alert when an inbound server aborts.

An Oracle database generates a stateful XStream alert when the Streams pool memory usage exceeds the percentage specified by the STREAMS_POOL_USED_PCT metric. You can manage this metric with the SET_THRESHOLD procedure in the DBMS_SERVER_ALERT package.

You can view alerts in Oracle Enterprise Manager Cloud Control, or you can query the following data dictionary views:

- The DBA_OUTSTANDING_ALERTS view records current stateful alerts. The DBA_ALERT_HISTORY view records stateless alerts and stateful alerts that have been cleared. For example, if the memory usage in the Streams pool exceeds the specified threshold, then a stateful alert is recorded in the DBA_OUTSTANDING_ALERTS view.

- The DBA_ALERT_HISTORY data dictionary view shows alerts that have been cleared from the DBA_OUTSTANDING_ALERTS view. For example, if the memory usage in the Streams pool falls below the specified threshold, then the alert recorded in the DBA_OUTSTANDING_ALERTS view is cleared and moved to the DBA_ALERT_HISTORY view.

For example, to list the current stateful alerts, run the following query on the DBA_OUTSTANDING_ALERTS view:

COLUMN REASON HEADING 'Reason for Alert' FORMAT A35
COLUMN SUGGESTED_ACTION HEADING 'Suggested Response' FORMAT A35

SELECT REASON, SUGGESTED_ACTION
FROM DBA_OUTSTANDING_ALERTS
WHERE MODULE_ID LIKE '%XSTREAM%';

To list the stateless alerts and cleared XStream stateful alerts, run the following query on the DBA_ALERT_HISTORY view:

COLUMN REASON HEADING 'Reason for Alert' FORMAT A35
COLUMN SUGGESTED_ACTION HEADING 'Suggested Response' FORMAT A35

SELECT REASON, SUGGESTED_ACTION
FROM DBA_ALERT_HISTORY
WHERE MODULE_ID LIKE '%XSTREAM%';

See Also:

- Oracle Database 2 Day + Performance Tuning Guide for information about managing alerts and metric thresholds

- Oracle Database Administrator's Guide for information about alerts and for information about subscribing to the ALERT_QUE queue to receive notifications when new alerts are generated

- Oracle Database PL/SQL Packages and Types Reference for more information about the DBMS_SERVER_ALERT package

- "Configure the Streams pool"

Checking the Trace File and Alert Log for Problems

Messages about inbound server are recorded in trace files for the database in which the process is running. These trace file messages can help you to identify and resolve problems in an XStream In configuration.

All trace files for background processes are written to the Automatic Diagnostic Repository. The names of trace files are operating system specific, but each file usually includes the name of the process writing the file.

For example, on some operating systems, the trace file name for a process is sid_xxxx_iiiii.trc, where:

- sid is the system identifier for the database

- xxxx is the name of the process

- iiiii is the operating system process number

Also, you can set the write_alert_log parameter to y for both a capture process and an outbound server. When this parameter is set to y, which is the default setting, the alert log for the database contains messages about why the capture process or outbound server stopped.

You can control the information in the trace files by setting the trace_level inbound server apply parameter using the SET_PARAMETER procedure in the DBMS_XSTREAM_ADM package.

An inbound server is an Oracle background process named APnn, where nn can include letters and numbers. For example, on some operating systems, if the system identifier for a database running an inbound server is hqdb and the inbound server number is 01, then the trace file for the inbound server starts with hqdb_AP01.

An inbound server also uses other processes. Information about an inbound server might be recorded in the trace file for one or more of these processes. The process name of the reader server and apply servers is ASnn, where nn can include letters and numbers. So, on some operating systems, if the system identifier for a database running an inbound server is hqdb and the process number is 01, then the trace file that contains information about a process used by an inbound server starts with hqdb_AS01.

See Also:

- "Displaying Session Information for Inbound Servers"

- Oracle Database Administrator's Guide for more information about trace files and the alert log, and for more information about their names and locations

- Oracle Database PL/SQL Packages and Types Reference for more information about setting the trace_level apply parameter

- Your operating system specific Oracle documentation for more information about the names and locations of trace files

Problems and Solutions for XStream In

In general, you can troubleshoot XStream inbound servers in the same way that you troubleshoot Oracle Streams apply processes. For information, see Oracle Streams Concepts and Administration.

This section describes common problems and solutions specifically for XStream In.

This section contains the following topics:

- XStream In Cannot Identify an Inbound Server

- Inbound Server Encounters an ORA-03135 Error

XStream In Cannot Identify an Inbound Server

If an XStream In configuration cannot identify an inbound server, then the following error is returned:

ORA-26840: STREAMS unable to identify an apply for the source database "%s"

The following sections describe the possible problem and its solution.

Problem: Multiple Subscribers to the Inbound Server's Queue

The ORA-26840 error indicates that there are multiple subscribers to the queue used by the inbound server. Subscribers can include inbound servers, outbound servers, apply processes, and propagations.

To determine whether there are multiple subscribers to the inbound server's queue:

1. Connect to the inbound server database as the XStream administrator.
See Oracle Database Administrator's Guide for information about connecting to a database in SQL*Plus.

2. Run the following query:

SELECT OWNER, QUEUE_NAME, CONSUMER_NAME, ADDRESS
FROM DBA_QUEUE_SUBSCRIBERS;

You can add a WHERE clause to the query to limit the output to the inbound server's queue.

Solution

To correct the problem:

- If the query returns multiple subscribers to the inbound server's queue, then reconfigure the subscribers so that the inbound server is the only subscriber.

See Also:
Chapter 4, "Configuring XStream Out"

Inbound Server Encounters an ORA-03135 Error

An inbound server encounters the following error:

ORA-03135: connection lost contact

Problem: Connection Broken Between the Inbound Server and the Client Application

The ORA-03135 error indicates that the connection between the inbound server and the XStream client application was broken.

Solution

To correct the problem:

- Restart the XStream client application.

See Also:
Appendix A, "Sample XStream Client Application"

How to Get More Help with XStream In

You can check My Oracle Support at http://support.oracle.com for more solutions to your problem.

You can visit http://www.oracle.com/support/contact.html for more information about Oracle Support.

Part IV

Appendixes

This part contains the following appendix:

- Appendix A, "Sample XStream Client Application,"

- Appendix B, "XStream Out Restrictions,"

- Appendix C, "XStream In Restrictions,"

A Sample XStream Client Application

This chapter describes configuring the Oracle Database components that are used by XStream. This chapter also includes sample client applications that communicate with an XStream outbound server and inbound server.

This chapter contains these topics:

- About the Sample XStream Client Application

- Sample XStream Client Application for the Oracle Call Interface API

- Sample XStream Client Application for the Java API

See Also:

- Chapter 3, "XStream Out Concepts"

- "XStream Use Cases"

- Oracle Call Interface Programmer's Guide

- Oracle Database XStream Java API Reference

About the Sample XStream Client Application

This section describes a sample XStream client application. This application illustrates the basic tasks that are required of an XStream Out and XStream In application.

The application performs the following tasks:

- It attaches to an XStream outbound server and inbound server and waits for LCRs from the outbound server. The outbound server and inbound server are in two different databases.

- When it receives an LCR from the outbound server, it immediately sends the LCR to the inbound server.

- It periodically gets the processed low position from the inbound server and sends this value to the outbound server.

- It periodically sends a "ping" LCR from the outbound server to the inbound server to move the inbound server's processed low position forward in times of low activity.

In an XStream Out configuration that does not send LCRs to an inbound server, the client application must obtain the processed low position in another way.

This application waits indefinitely for transactions from the outbound server. To interrupt the application, enter the interrupt command for your operating system. For example, the interrupt command on some operating systems is control-C. If the program is restarted, then the outbound server starts sending LCRs from the processed low position that was set during the previous run.

Figure A-1 provides an overview of the XStream environment configured in this section.

Figure A-1 Sample XStream Configuration

Before running the sample application, ensure that the following components exist:

- Two Oracle databases with network connectivity between them

- An XStream administrator on both databases

- An outbound server configuration on one database, including a capture process, queue, and outbound server

- An inbound server configuration on another database

If you are running the sample application with a multitenant container database (CDB), then ensure that the client application connects to the correct container:

- When the client application connects to the outbound server, it must connect to the root.

- When the client application connects to the inbound server, it must connect to the container in which the inbound server was created.

The sample applications in the following sections perform the same tasks. One sample application uses the OCI API, and the other uses the Java API.

- Sample XStream Client Application for the Oracle Call Interface API

- Sample XStream Client Application for the Java API

Note:
An Oracle Database installation includes several XStream demos. These demos are in the following location:

$ORACLE_HOME/rdbms/demo/xstream

See Also:

- "Position Order in an LCR Stream"

- Chapter 4, "Configuring XStream Out"

- Chapter 9, "Configuring XStream In"

- Oracle Call Interface Programmer's Guide

- Oracle Database XStream Java API Reference

- Oracle Database PL/SQL Packages and Types Reference

Sample XStream Client Application for the Oracle Call Interface API

To run the sample XStream client application for the OCI API, compile and link the application file, and enter the following on a command line:

xio -ob_svr xout_name -ob_db sn_xout_db -ob_usr xout_cu -ob_pwd xout_cu_pass
-ib_svr xin_name -ib_db sn_xin_db -ib_usr xin_au -ib_pwd xin_au_pass

Substitute the appropriate values for the following placeholders:

- xout_name is the name of the outbound server.

- sn_xout_db is the service name for the outbound server's database.

- xout_cu is the outbound server's connect user.

- xout_cu_pass is the password for the outbound server's connect user.

- xin_name is the name of the inbound server.

- sn_xin_db is the service name for the inbound server's database.

- xin_au is the inbound server's apply user.

- xin_au_pass is the password for the inbound server's apply user.

When the sample client application is running, it prints information about the row LCRs it is processing. The output looks similar to the following:

----------- ROW LCR Header  -----------------
src_db_name=DB.EXAMPLE.COM
cmd_type=UPDATE txid=17.0.74
owner=HR oname=COUNTRIES

----------- ROW LCR Header  -----------------
src_db_name=DB.EXAMPLE.COM
cmd_type=COMMIT txid=17.0.74

----------- ROW LCR Header  -----------------
src_db_name=DB.EXAMPLE.COM
cmd_type=UPDATE txid=12.25.77
owner=OE oname=ORDERS

----------- ROW LCR Header  -----------------
src_db_name=DB.EXAMPLE.COM
cmd_type=UPDATE txid=12.25.77
owner=OE oname=ORDERS

This output contains the following information for each row LCR:

- src_db_name shows the source database for the change encapsulated in the row LCR.

- cmd_type shows the type of SQL statement that made the change.

- txid shows the transaction ID of the transaction that includes the row LCR.

- owner shows the owner of the database object that was changed.

- oname shows the name of the database object that was changed.

This demo is available in the following location:

$ORACLE_HOME/rdbms/demo/xstream/oci

The file name for the demo is xio.c. See the README.txt file in the demo directory for more information about compiling and running the application.

The code for the sample application that uses the OCI API follows:

#ifndef OCI_ORACLE
#include <oci.h>
#endif

#ifndef _STDIO_H
#include <stdio.h>
#endif

#ifndef _STDLIB_H
#include <stdlib.h>
#endif

#ifndef _STRING_H
#include <string.h>
#endif

#ifndef _MALLOC_H
#include <malloc.h>
#endif

/*----------------------------------------------------------------------
*           Internal structures
*----------------------------------------------------------------------*/

#define M_DBNAME_LEN    (128)

typedef struct conn_info                                     /* connect info */
{
oratext * user;
ub4       userlen;
oratext * passw;
ub4       passwlen;
oratext * dbname;
ub4       dbnamelen;
oratext * svrnm;
ub4       svrnmlen;
} conn_info_t;

typedef struct params
{
conn_info_t  xout;                                        /* outbound info */
conn_info_t  xin;                                          /* inbound info */
} params_t;

typedef struct oci                                            /* OCI handles */
{
OCIEnv      *envp;                                   /* Environment handle */
OCIError    *errp;                                         /* Error handle */
OCIServer   *srvp;                                        /* Server handle */
OCISvcCtx   *svcp;                                       /* Service handle */
OCISession  *authp;
OCIStmt    *stmtp;
boolean     attached;
boolean     outbound;
} oci_t;

static void connect_db(conn_info_t *opt_params_p, oci_t ** ocip, ub2 char_csid,
ub2 nchar_csid);
static void disconnect_db(oci_t * ocip);
static void ocierror(oci_t * ocip, char * msg);
static void attach(oci_t * ocip, conn_info_t *conn, boolean outbound);
static void detach(oci_t *ocip);
static void get_lcrs(oci_t *xin_ocip, oci_t *xout_ocip);
static void get_chunks(oci_t *xin_ocip, oci_t *xout_ocip);
static void print_lcr(oci_t *ocip, void *lcrp, ub1 lcrtype,
oratext **src_db_name, ub2  *src_db_namel);
static void print_chunk (ub1 *chunk_ptr, ub4 chunk_len, ub2 dty);
static void get_inputs(conn_info_t *xout_params, conn_info_t *xin_params,
int argc, char ** argv);
static void get_db_charsets(conn_info_t *params_p, ub2 *char_csid,
ub2 *nchar_csid);
static void set_client_charset(oci_t *outbound_ocip);

#define OCICALL(ocip, function) do {\
sword status=function;\
if (OCI_SUCCESS==status) break;\
else if (OCI_ERROR==status) \
{ocierror(ocip, (char *)"OCI_ERROR");\
exit(1);}\
else {printf("Error encountered %d\n", status);\
exit(1);}\
} while(0)

/*---------------------------------------------------------------------
*                M A I N   P R O G R A M
*---------------------------------------------------------------------*/
main(int argc, char **argv)
{
/* Outbound and inbound connection info */
conn_info_t   xout_params;
conn_info_t   xin_params;
oci_t        *xout_ocip = (oci_t *)NULL;
oci_t        *xin_ocip = (oci_t *)NULL;
ub2           obdb_char_csid = 0;                 /* outbound db char csid */
ub2           obdb_nchar_csid = 0;               /* outbound db nchar csid */

/* parse command line arguments */
get_inputs(&xout_params, &xin_params, argc, argv);

/* Get the outbound database CHAR and NCHAR character set info */
get_db_charsets(&xout_params, &obdb_char_csid, &obdb_nchar_csid);

/* Connect to the outbound db and set the client env to the outbound charsets
* to minimize character conversion when transferring LCRs from outbound
* directly to inbound server.
*/
connect_db(&xout_params, &xout_ocip, obdb_char_csid, obdb_nchar_csid);

/* Attach to outbound server */
attach(xout_ocip, &xout_params, TRUE);

/* connect to inbound db and set the client charsets the same as the
* outbound db charsets.
*/
connect_db(&xin_params, &xin_ocip, obdb_char_csid, obdb_nchar_csid);

/* Attach to inbound server */
attach(xin_ocip, &xin_params, FALSE);

/* Get lcrs from outbound server and send to inbound server */
get_lcrs(xin_ocip, xout_ocip);

/* Detach from XStream servers */
detach(xout_ocip);
detach(xin_ocip);

/* Disconnect from both databases */
disconnect_db(xout_ocip);
disconnect_db(xin_ocip);

free(xout_ocip);
free(xin_ocip);
exit (0);
}

/*---------------------------------------------------------------------
* connect_db - Connect to the database and set the env to the given
* char and nchar character set ids.
*---------------------------------------------------------------------*/
static void connect_db(conn_info_t *params_p, oci_t **ociptr, ub2 char_csid,
ub2 nchar_csid)
{
oci_t        *ocip;

printf ("Connect to Oracle as %.*s@%.*s ",
params_p->userlen, params_p->user,
params_p->dbnamelen, params_p->dbname);

if (char_csid && nchar_csid)
printf ("using char csid=%d and nchar csid=%d", char_csid, nchar_csid);

printf("\n");

ocip = (oci_t *)malloc(sizeof(oci_t));

if (OCIEnvNlsCreate(&ocip->envp, OCI_OBJECT, (dvoid *)0,
(dvoid * (*)(dvoid *, size_t)) 0,
(dvoid * (*)(dvoid *, dvoid *, size_t))0,
(void (*)(dvoid *, dvoid *)) 0,
(size_t) 0, (dvoid **) 0, char_csid, nchar_csid))
{
ocierror(ocip, (char *)"OCIEnvCreate() failed");
}

if (OCIHandleAlloc((dvoid *) ocip->envp, (dvoid **) &ocip->errp,
(ub4) OCI_HTYPE_ERROR, (size_t) 0, (dvoid **) 0))
{
ocierror(ocip, (char *)"OCIHandleAlloc(OCI_HTYPE_ERROR) failed");
}

/* Logon to database */
OCICALL(ocip,
OCILogon(ocip->envp, ocip->errp, &ocip->svcp,
params_p->user, params_p->userlen,
params_p->passw, params_p->passwlen,
params_p->dbname, params_p->dbnamelen));

/* allocate the server handle */
OCICALL(ocip,
OCIHandleAlloc((dvoid *) ocip->envp, (dvoid **) &ocip->srvp,
OCI_HTYPE_SERVER, (size_t) 0, (dvoid **) 0));

OCICALL(ocip,
OCIHandleAlloc((dvoid *) ocip->envp, (dvoid **) &ocip->stmtp,
(ub4) OCI_HTYPE_STMT, (size_t) 0, (dvoid **) 0));

if (*ociptr == (oci_t *)NULL)
{
*ociptr = ocip;
}
}

/*---------------------------------------------------------------------
* get_db_charsets - Get the database CHAR and NCHAR character set ids.
*---------------------------------------------------------------------*/
static const oratext GET_DB_CHARSETS[] =  \
"select parameter, value from nls_database_parameters where parameter = \
'NLS_CHARACTERSET' or parameter = 'NLS_NCHAR_CHARACTERSET'";

#define PARM_BUFLEN      (30)

static void get_db_charsets(conn_info_t *params_p, ub2 *char_csid,
ub2 *nchar_csid)
{
OCIDefine  *defnp1 = (OCIDefine *) NULL;
OCIDefine  *defnp2 = (OCIDefine *) NULL;
oratext     parm[PARM_BUFLEN];
oratext     value[OCI_NLS_MAXBUFSZ];
ub2         parm_len = 0;
ub2         value_len = 0;
oci_t       ocistruct;
oci_t      *ocip = &ocistruct;

*char_csid = 0;
*nchar_csid = 0;
memset (ocip, 0, sizeof(ocistruct));

if (OCIEnvCreate(&ocip->envp, OCI_OBJECT, (dvoid *)0,
(dvoid * (*)(dvoid *, size_t)) 0,
(dvoid * (*)(dvoid *, dvoid *, size_t))0,
(void (*)(dvoid *, dvoid *)) 0,
(size_t) 0, (dvoid **) 0))
{
ocierror(ocip, (char *)"OCIEnvCreate() failed");
}

if (OCIHandleAlloc((dvoid *) ocip->envp, (dvoid **) &ocip->errp,
(ub4) OCI_HTYPE_ERROR, (size_t) 0, (dvoid **) 0))
{
ocierror(ocip, (char *)"OCIHandleAlloc(OCI_HTYPE_ERROR) failed");
}

OCICALL(ocip,
OCILogon(ocip->envp, ocip->errp, &ocip->svcp,
params_p->user, params_p->userlen,
params_p->passw, params_p->passwlen,
params_p->dbname, params_p->dbnamelen));

OCICALL(ocip,
OCIHandleAlloc((dvoid *) ocip->envp, (dvoid **) &ocip->stmtp,
(ub4) OCI_HTYPE_STMT, (size_t) 0, (dvoid **) 0));

/* Execute stmt to select the db nls char and nchar character set */
OCICALL(ocip,
OCIStmtPrepare(ocip->stmtp, ocip->errp,
(CONST text *)GET_DB_CHARSETS,
(ub4)strlen((char *)GET_DB_CHARSETS),
(ub4)OCI_NTV_SYNTAX, (ub4)OCI_DEFAULT));

OCICALL(ocip,
OCIDefineByPos(ocip->stmtp, &defnp1,
ocip->errp, (ub4) 1, parm,
PARM_BUFLEN, SQLT_CHR, (void*) 0,
&parm_len, (ub2 *)0, OCI_DEFAULT));

OCICALL(ocip,
OCIDefineByPos(ocip->stmtp, &defnp2,
ocip->errp, (ub4) 2, value,
OCI_NLS_MAXBUFSZ, SQLT_CHR, (void*) 0,
&value_len, (ub2 *)0, OCI_DEFAULT));

OCICALL(ocip,
OCIStmtExecute(ocip->svcp, ocip->stmtp,
ocip->errp, (ub4)0, (ub4)0,
(const OCISnapshot *)0,
(OCISnapshot *)0, (ub4)OCI_DEFAULT));

while (OCIStmtFetch(ocip->stmtp, ocip->errp, 1,
OCI_FETCH_NEXT, OCI_DEFAULT) == OCI_SUCCESS)
{
value[value_len] = '\0';
if (parm_len == strlen("NLS_CHARACTERSET") &&
!memcmp(parm, "NLS_CHARACTERSET", parm_len))
{
*char_csid = OCINlsCharSetNameToId(ocip->envp, value);
printf("Outbound database NLS_CHARACTERSET = %.*s (csid = %d) \n",
value_len, value, *char_csid);
}
else if (parm_len == strlen("NLS_NCHAR_CHARACTERSET") &&
!memcmp(parm, "NLS_NCHAR_CHARACTERSET", parm_len))
{
*nchar_csid = OCINlsCharSetNameToId(ocip->envp, value);
printf("Outbound database NLS_NCHAR_CHARACTERSET = %.*s (csid = %d) \n",
value_len, value, *nchar_csid);
}
}

disconnect_db(ocip);
}

/*---------------------------------------------------------------------
* attach - Attach to XStream server specified in connection info
*---------------------------------------------------------------------*/
static void attach(oci_t * ocip, conn_info_t *conn, boolean outbound)
{
sword       err;

printf ("Attach to XStream %s server '%.*s'\n",
outbound ? "outbound" : "inbound",
conn->svrnmlen, conn->svrnm);

if (outbound)
{
OCICALL(ocip,
OCIXStreamOutAttach(ocip->svcp, ocip->errp, conn->svrnm,
(ub2)conn->svrnmlen, (ub1 *)0, 0, OCI_DEFAULT));
}
else
{
OCICALL(ocip,
OCIXStreamInAttach(ocip->svcp, ocip->errp, conn->svrnm,
(ub2)conn->svrnmlen,
(oratext *)"From_XOUT", 9,
(ub1 *)0, 0, OCI_DEFAULT));
}

ocip->attached = TRUE;
ocip->outbound = outbound;
}

/*---------------------------------------------------------------------
* ping_svr - Ping inbound server by sending a commit LCR.
*---------------------------------------------------------------------*/
static void ping_svr(oci_t *xin_ocip, void *commit_lcr,
ub1 *cmtpos, ub2 cmtpos_len,
oratext *source_db, ub2 source_db_len)
{
OCIDate     src_time;
oratext     txid[128];

OCICALL(xin_ocip, OCIDateSysDate(xin_ocip->errp, &src_time));
sprintf((char *)txid, "Ping %2d:%2d:%2d",
src_time.OCIDateTime.OCITimeHH,
src_time.OCIDateTime.OCITimeMI,
src_time.OCIDateTime.OCITimeSS);

/* Initialize LCR with new txid and commit position */
OCICALL(xin_ocip,
OCILCRHeaderSet(xin_ocip->svcp, xin_ocip->errp,
source_db, source_db_len,
(oratext *)OCI_LCR_ROW_CMD_COMMIT,
(ub2)strlen(OCI_LCR_ROW_CMD_COMMIT),
(oratext *)0, 0,                     /* null owner */
(oratext *)0, 0,                    /* null object */
(ub1 *)0, 0,                           /* null tag */
txid, (ub2)strlen((char *)txid),
&src_time, cmtpos, cmtpos_len,
0, commit_lcr, OCI_DEFAULT));

/* Send commit lcr to inbound server. */
if (OCIXStreamInLCRSend(xin_ocip->svcp, xin_ocip->errp, commit_lcr,
OCI_LCR_XROW, 0, OCI_DEFAULT) == OCI_ERROR)
{
ocierror(xin_ocip, (char *)"OCIXStreamInLCRSend failed in ping_svr()");
}
}

/*---------------------------------------------------------------------
* get_lcrs - Get LCRs from outbound server and send to inbound server.
*---------------------------------------------------------------------*/
static void get_lcrs(oci_t *xin_ocip, oci_t *xout_ocip)
{
sword       status = OCI_SUCCESS;
void       *lcr;
ub1         lcrtype;
oraub8      flag;
ub1         proclwm[OCI_LCR_MAX_POSITION_LEN];
ub2         proclwm_len = 0;
ub1         sv_pingpos[OCI_LCR_MAX_POSITION_LEN];
ub2         sv_pingpos_len = 0;
ub1         fetchlwm[OCI_LCR_MAX_POSITION_LEN];
ub2         fetchlwm_len = 0;
void       *commit_lcr = (void *)0;
oratext    *lcr_srcdb = (oratext *)0;
ub2         lcr_srcdb_len = 0;
oratext     source_db[M_DBNAME_LEN];
ub2         source_db_len = 0;
ub4         lcrcnt = 0;

/* create an lcr to ping the inbound server periodically by sending a
* commit lcr.
*/
commit_lcr = (void*)0;
OCICALL(xin_ocip,
OCILCRNew(xin_ocip->svcp, xin_ocip->errp, OCI_DURATION_SESSION,
OCI_LCR_XROW, &commit_lcr, OCI_DEFAULT));

while (status == OCI_SUCCESS)
{
lcrcnt = 0;                         /* reset lcr count before each batch */

while ((status =
OCIXStreamOutLCRReceive(xout_ocip->svcp, xout_ocip->errp,
&lcr, &lcrtype, &flag,
fetchlwm, &fetchlwm_len, OCI_DEFAULT))
== OCI_STILL_EXECUTING)
{
lcrcnt++;

/* print header of LCR just received */
print_lcr(xout_ocip, lcr, lcrtype, &lcr_srcdb, &lcr_srcdb_len);

/* save the source db to construct ping lcr later */
if (!source_db_len && lcr_srcdb_len)
{
memcpy(source_db, lcr_srcdb, lcr_srcdb_len);
source_db_len = lcr_srcdb_len;
}

/* send the LCR just received */
if (OCIXStreamInLCRSend(xin_ocip->svcp, xin_ocip->errp,
lcr, lcrtype, flag, OCI_DEFAULT) == OCI_ERROR)
{
ocierror(xin_ocip, (char *)"OCIXStreamInLCRSend failed");
}

/* If LCR has chunked columns (i.e, has LOB/Long/XMLType columns) */
if (flag & OCI_XSTREAM_MORE_ROW_DATA)
{
/* receive and send chunked columns */
get_chunks(xin_ocip, xout_ocip);
}
}

if (status == OCI_ERROR)
ocierror(xout_ocip, (char *)"OCIXStreamOutLCRReceive failed");

/* clear the saved ping position if we just received some new lcrs */
if (lcrcnt)
{
sv_pingpos_len = 0;
}

/* If no lcrs received during previous WHILE loop and got a new fetch
* LWM then send a commit lcr to ping the inbound server with the new
* fetch LWM position.
*/
else if (fetchlwm_len > 0 && source_db_len > 0 &&
(fetchlwm_len != sv_pingpos_len ||
memcmp(sv_pingpos, fetchlwm, fetchlwm_len)))
{
/* To ensure we don't send multiple lcrs with duplicate position, send
* a new ping only if we have saved the last ping position.
*/
if (sv_pingpos_len > 0)
{
ping_svr(xin_ocip, commit_lcr, fetchlwm, fetchlwm_len,
source_db, source_db_len);
}

/* save the position just sent to inbound server */
memcpy(sv_pingpos, fetchlwm, fetchlwm_len);
sv_pingpos_len = fetchlwm_len;
}

/* flush inbound network to flush all lcrs to inbound server */
OCICALL(xin_ocip,
OCIXStreamInFlush(xin_ocip->svcp, xin_ocip->errp, OCI_DEFAULT));

/* get processed LWM of inbound server */
OCICALL(xin_ocip,
OCIXStreamInProcessedLWMGet(xin_ocip->svcp, xin_ocip->errp,
proclwm, &proclwm_len, OCI_DEFAULT));

if (proclwm_len > 0)
{
/* Set processed LWM for outbound server */
OCICALL(xout_ocip,
OCIXStreamOutProcessedLWMSet(xout_ocip->svcp, xout_ocip->errp,
proclwm, proclwm_len, OCI_DEFAULT));
}
}

if (status != OCI_SUCCESS)
ocierror(xout_ocip, (char *)"get_lcrs() encounters error");
}

/*---------------------------------------------------------------------
* get_chunks - Get each chunk for the current LCR and send it to
*              the inbound server.
*---------------------------------------------------------------------*/
static void get_chunks(oci_t *xin_ocip, oci_t *xout_ocip)
{
oratext *colname;
ub2      colname_len;
ub2      coldty;
oraub8   col_flags;
ub2      col_csid;
ub4      chunk_len;
ub1     *chunk_ptr;
oraub8   row_flag;
sword    err;
sb4      rtncode;

do
{
/* Get a chunk from outbound server */
OCICALL(xout_ocip,
OCIXStreamOutChunkReceive(xout_ocip->svcp, xout_ocip->errp,
&colname, &colname_len, &coldty,
&col_flags, &col_csid, &chunk_len,
&chunk_ptr, &row_flag, OCI_DEFAULT));

/* print chunked column info */
printf(
"  Chunked column name=%.*s DTY=%d  chunk len=%d csid=%d col_flag=0x%lx\n",
colname_len, colname, coldty, chunk_len, col_csid, col_flags);

/* print chunk data */
print_chunk(chunk_ptr, chunk_len, coldty);

/* Send the chunk just received to inbound server */
OCICALL(xin_ocip,
OCIXStreamInChunkSend(xin_ocip->svcp, xin_ocip->errp, colname,
colname_len, coldty, col_flags,
col_csid, chunk_len, chunk_ptr,
row_flag, OCI_DEFAULT));

} while (row_flag & OCI_XSTREAM_MORE_ROW_DATA);
}

/*---------------------------------------------------------------------
* print_chunk - Print chunked column information. Only print the first
*               50 bytes for each chunk.
*---------------------------------------------------------------------*/
static void print_chunk (ub1 *chunk_ptr, ub4 chunk_len, ub2 dty)
{
#define MAX_PRINT_BYTES     (50)          /* print max of 50 bytes per chunk */

ub4  print_bytes;

if (chunk_len == 0)
return;

print_bytes = chunk_len > MAX_PRINT_BYTES ? MAX_PRINT_BYTES : chunk_len;

printf("  Data = ");
if (dty == SQLT_CHR)
printf("%.*s", print_bytes, chunk_ptr);
else
{
ub2  idx;

for (idx = 0; idx < print_bytes; idx++)
printf("%02x", chunk_ptr[idx]);
}
printf("\n");
}

/*---------------------------------------------------------------------
* print_lcr - Print header information of given lcr.
*---------------------------------------------------------------------*/
static void print_lcr(oci_t *ocip, void *lcrp, ub1 lcrtype,
oratext **src_db_name, ub2  *src_db_namel)
{
oratext     *cmd_type;
ub2          cmd_type_len;
oratext     *owner;
ub2          ownerl;
oratext     *oname;
ub2          onamel;
oratext     *txid;
ub2          txidl;
sword        ret;

printf("\n ----------- %s LCR Header  -----------------\n",
lcrtype == OCI_LCR_XDDL ? "DDL" : "ROW");

/* Get LCR Header information */
ret = OCILCRHeaderGet(ocip->svcp, ocip->errp,
src_db_name, src_db_namel,              /* source db */
&cmd_type, &cmd_type_len,            /* command type */
&owner, &ownerl,                       /* owner name */
&oname, &onamel,                      /* object name */
(ub1 **)0, (ub2 *)0,                      /* lcr tag */
&txid, &txidl, (OCIDate *)0,   /* txn id  & src time */
(ub2 *)0, (ub2 *)0,              /* OLD/NEW col cnts */
(ub1 **)0, (ub2 *)0,                 /* LCR position */
(oraub8*)0, lcrp, OCI_DEFAULT);

if (ret != OCI_SUCCESS)
ocierror(ocip, (char *)"OCILCRHeaderGet failed");
else
{
printf("  src_db_name=%.*s\n  cmd_type=%.*s txid=%.*s\n",
*src_db_namel, *src_db_name, cmd_type_len, cmd_type, txidl, txid );

if (ownerl > 0)
printf("  owner=%.*s oname=%.*s \n", ownerl, owner, onamel, oname);
}
}

/*---------------------------------------------------------------------
* detach - Detach from XStream server
*---------------------------------------------------------------------*/
static void detach(oci_t * ocip)
{
sword  err = OCI_SUCCESS;

printf ("Detach from XStream %s server\n",
ocip->outbound ? "outbound" : "inbound" );

if (ocip->outbound)
{
OCICALL(ocip, OCIXStreamOutDetach(ocip->svcp, ocip->errp, OCI_DEFAULT));
}
else
{
OCICALL(ocip, OCIXStreamInDetach(ocip->svcp, ocip->errp,
(ub1 *)0, (ub2 *)0,    /* processed LWM */
OCI_DEFAULT));
}
}

/*---------------------------------------------------------------------
* disconnect_db  - Logoff from the database
*---------------------------------------------------------------------*/
static void disconnect_db(oci_t * ocip)
{
if (OCILogoff(ocip->svcp, ocip->errp))
{
ocierror(ocip, (char *)"OCILogoff() failed");
}

if (ocip->errp)
OCIHandleFree((dvoid *) ocip->errp, (ub4) OCI_HTYPE_ERROR);

if (ocip->envp)
OCIHandleFree((dvoid *) ocip->envp, (ub4) OCI_HTYPE_ENV);
}

/*---------------------------------------------------------------------
* ocierror - Print error status and exit program
*---------------------------------------------------------------------*/
static void ocierror(oci_t * ocip, char * msg)
{
sb4 errcode=0;
text bufp[4096];

if (ocip->errp)
{
OCIErrorGet((dvoid *) ocip->errp, (ub4) 1, (text *) NULL, &errcode,
bufp, (ub4) 4096, (ub4) OCI_HTYPE_ERROR);
printf("%s\n%s", msg, bufp);
}
else
puts(msg);

printf ("\n");
exit(1);
}

/*--------------------------------------------------------------------
* print_usage - Print command usage
*---------------------------------------------------------------------*/
static void print_usage(int exitcode)
{
puts("\nUsage: xio -ob_svr <outbound_svr> -ob_db <outbound_db>\n"
"           -ob_usr <conn_user> -ob_pwd <conn_user_pwd>\n"
"           -ib_svr <inbound_svr> -ib_db <inbound_db>\n"
"           -ib_usr <apply_user> -ib_pwd <apply_user_pwd>\n");
puts("  ob_svr  : outbound server name\n"
"  ob_db   : database name of outbound server\n"
"  ob_usr  : connect user to outbound server\n"
"  ob_pwd  : password of outbound's connect user\n"
"  ib_svr  : inbound server name\n"
"  ib_db   : database name of inbound server\n"
"  ib_usr  : apply user for inbound server\n"
"  ib_pwd  : password of inbound's apply user\n");

exit(exitcode);
}

/*--------------------------------------------------------------------
* get_inputs - Get user inputs from command line
*---------------------------------------------------------------------*/
static void get_inputs(conn_info_t *xout_params, conn_info_t *xin_params,
int argc, char ** argv)
{
char * option;
char * value;

memset (xout_params, 0, sizeof(*xout_params));
memset (xin_params, 0, sizeof(*xin_params));
while(--argc)
{
/* get the option name */
argv++;
option = *argv;

/* check that the option begins with a "-" */
if (!strncmp(option, (char *)"-", 1))
{
option ++;
}
else
{
printf("Error: bad argument '%s'\n", option);
print_usage(1);
}

/* get the value of the option */
--argc;
argv++;

value = *argv;

if (!strncmp(option, (char *)"ob_db", 5))
{
xout_params->dbname = (oratext *)value;
xout_params->dbnamelen = (ub4)strlen(value);
}
else if (!strncmp(option, (char *)"ob_usr", 6))
{
xout_params->user = (oratext *)value;
xout_params->userlen = (ub4)strlen(value);
}
else if (!strncmp(option, (char *)"ob_pwd", 6))
{
xout_params->passw = (oratext *)value;
xout_params->passwlen = (ub4)strlen(value);
}
else if (!strncmp(option, (char *)"ob_svr", 6))
{
xout_params->svrnm = (oratext *)value;
xout_params->svrnmlen = (ub4)strlen(value);
}
else if (!strncmp(option, (char *)"ib_db", 5))
{
xin_params->dbname = (oratext *)value;
xin_params->dbnamelen = (ub4)strlen(value);
}
else if (!strncmp(option, (char *)"ib_usr", 6))
{
xin_params->user = (oratext *)value;
xin_params->userlen = (ub4)strlen(value);
}
else if (!strncmp(option, (char *)"ib_pwd", 6))
{
xin_params->passw = (oratext *)value;
xin_params->passwlen = (ub4)strlen(value);
}
else if (!strncmp(option, (char *)"ib_svr", 6))
{
xin_params->svrnm = (oratext *)value;
xin_params->svrnmlen = (ub4)strlen(value);
}
else
{
printf("Error: unknown option '%s'.\n", option);
print_usage(1);
}
}

/* print usage and exit if any argument is not specified */
if (!xout_params->svrnmlen || !xout_params->passwlen ||
!xout_params->userlen || !xout_params->dbnamelen ||
!xin_params->svrnmlen || !xin_params->passwlen ||
!xin_params->userlen || !xin_params->dbnamelen)
{
printf("Error: missing command arguments. \n");
print_usage(1);
}
}

Sample XStream Client Application for the Java API

To run the sample XStream client application for the Java API, compile and link the application file, and enter the following on a command line:

java xio xsin_oraclesid xsin_host xsin_port xsin_username
xsin_passwd xin_servername xsout_oraclesid xsout_host xsout_port
xsout_username xsout_passwd xsout_servername

Substitute the appropriate values for the following placeholders:

- xsin_oraclesid is the Oracle SID of the inbound server's database.

- xsin_host is the host name of the computer system running the inbound server.

- xsin_port is the port number of the listener for the inbound server's database.

- xsin_username is the inbound server's apply user.

- xsin_passwd is the password for the inbound server's apply user.

- xin_servername is the name of the inbound server.

- xsout_oraclesid is the Oracle SID of the outbound server's database.

- xsout_host is the host name of the computer system running the outbound server.

- xsout_port is the port number of the listener for the outbound server's database.

- xsout_username is the outbound server's connect user.

- xsout_passwd is the password for the outbound server's connect user.

- xsout_servername is the name of the outbound server.

When the sample client application is running, it prints information about attaching to the inbound server and outbound server, along with the last position for each server. The output looks similar to the following:

xsin_host = server2.example.com
xsin_port = 1482
xsin_ora_sid = db2
xsin connection url: jdbc:oracle:oci:@server2.example.com:1482:db2
xsout_host = server1.example.com
xsout_port = 1481
xsout_ora_sid = db1
xsout connection url: jdbc:oracle:oci:@server1.example.com:1481:db1
Attached to inbound server:xin
Inbound Server Last Position is: 0000000920250000000100000001000000092025000000010000000101
Attached to outbound server:xout
Last Position is: 0000000920250000000100000001000000092025000000010000000101

This demo is available in the following location:

$ORACLE_HOME/rdbms/demo/xstream/java

The file name for the demo is xio.java. See the README.txt file in the demo directory for more information about compiling and running the application.

The code for the sample application that uses the Java API follows:

import oracle.streams.*;
import oracle.jdbc.internal.OracleConnection;
import oracle.jdbc.*;
import oracle.sql.*;
import java.sql.*;
import java.util.*;

public class xio
{
public static String xsinusername = null;
public static String xsinpasswd = null;
public static String xsinName = null;
public static String xsoutusername = null;
public static String xsoutpasswd = null;
public static String xsoutName = null;
public static String in_url = null;
public static String out_url = null;
public static Connection in_conn = null;
public static Connection out_conn = null;
public static XStreamIn xsIn = null;
public static XStreamOut xsOut = null;
public static byte[] lastPosition = null;
public static byte[] processedLowPosition = null;

public static void main(String args[])
{
// get connection url to inbound and outbound server
in_url = parseXSInArguments(args);
out_url = parseXSOutArguments(args);

// create connection to inbound and outbound server
in_conn = createConnection(in_url, xsinusername, xsinpasswd);
out_conn = createConnection(out_url, xsoutusername, xsoutpasswd);

// attach to inbound and outbound server
xsIn = attachInbound(in_conn);
xsOut = attachOutbound(out_conn);

// main loop to get lcrs
get_lcrs(xsIn, xsOut);

// detach from inbound and outbound server
detachInbound(xsIn);
detachOutbound(xsOut);
}

// parse the arguments to get the conncetion url to inbound db
public static String parseXSInArguments(String args[])
{
String trace, pref;
String orasid, host, port;

if (args.length != 12)
{
printUsage();
System.exit(0);
}

orasid = args[0];
host = args[1];
port = args[2];
xsinusername = args[3];
xsinpasswd = args[4];
xsinName = args[5];

System.out.println("xsin_host = "+host);
System.out.println("xsin_port = "+port);
System.out.println("xsin_ora_sid = "+orasid);

String in_url = "jdbc:oracle:oci:@"+host+":"+port+":"+orasid;
System.out.println("xsin connection url: "+ in_url);

return in_url;
}

// parse the arguments to get the conncetion url to outbound db
public static String parseXSOutArguments(String args[])
{
String trace, pref;
String orasid, host, port;

if (args.length != 12)
{
printUsage();
System.exit(0);
}

orasid = args[6];
host = args[7];
port = args[8];
xsoutusername = args[9];
xsoutpasswd = args[10];
xsoutName = args[11];

System.out.println("xsout_host = "+host);
System.out.println("xsout_port = "+port);
System.out.println("xsout_ora_sid = "+orasid);

String out_url = "jdbc:oracle:oci:@"+host+":"+port+":"+orasid;
System.out.println("xsout connection url: "+ out_url);

return out_url;
}

// print out sample program usage message
public static void printUsage()
{
System.out.println("");
System.out.println("Usage: java xio "+"<xsin_oraclesid> " + "<xsin_host> "
+ "<xsin_port> ");
System.out.println("                "+"<xsin_username> " + "<xsin_passwd> "
+ "<xsin_servername> ");
System.out.println("                "+"<xsout_oraclesid> " + "<xsout_host> "
+ "<xsout_port> ");
System.out.println("                "+"<xsout_username> " + "<xsout_passwd> "
+ "<xsout_servername> ");
}

// create a connection to an Oracle Database
public static Connection createConnection(String url,
String username,
String passwd)
{
try
{
DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
return DriverManager.getConnection(url, username, passwd);
}
catch(Exception e)
{
System.out.println("fail to establish DB connection to: " +url);
e.printStackTrace();
return null;
}
}

// attach to the XStream Inbound Server
public static XStreamIn attachInbound(Connection in_conn)
{
XStreamIn xsIn = null;
try
{
xsIn = XStreamIn.attach((OracleConnection)in_conn, xsinName,
"XSDEMOINCLIENT" , XStreamIn.DEFAULT_MODE);

// use last position to decide where should we start sending LCRs
lastPosition = xsIn.getLastPosition();
System.out.println("Attached to inbound server:"+xsinName);
System.out.print("Inbound Server Last Position is: ");
if (null == lastPosition)
{
System.out.println("null");
}
else
{
printHex(lastPosition);
}
return xsIn;
}
catch(Exception e)
{
System.out.println("cannot attach to inbound server: "+xsinName);
System.out.println(e.getMessage());
e.printStackTrace();
return null;
}
}

// attach to the XStream Outbound Server
public static XStreamOut attachOutbound(Connection out_conn)
{
XStreamOut xsOut = null;

try
{
// when attach to an outbound server, client needs to tell outbound
// server the last position.
xsOut = XStreamOut.attach((OracleConnection)out_conn, xsoutName,
lastPosition, XStreamOut.DEFAULT_MODE);
System.out.println("Attached to outbound server:"+xsoutName);
System.out.print("Last Position is: ");
if (lastPosition != null)
{
printHex(lastPosition);
}
else
{
System.out.println("NULL");
}
return xsOut;
}
catch(Exception e)
{
System.out.println("cannot attach to outbound server: "+xsoutName);
System.out.println(e.getMessage());
e.printStackTrace();
return null;
}
}

// detach from the XStream Inbound Server
public static void detachInbound(XStreamIn xsIn)
{
byte[] processedLowPosition = null;
try
{
processedLowPosition = xsIn.detach(XStreamIn.DEFAULT_MODE);
System.out.print("Inbound server processed low Position is: ");
if (processedLowPosition != null)
{
printHex(processedLowPosition);
}
else
{
System.out.println("NULL");
}
}
catch(Exception e)
{
System.out.println("cannot detach from the inbound server: "+xsinName);
System.out.println(e.getMessage());
e.printStackTrace();
}
}

// detach from the XStream Outbound Server
public static void detachOutbound(XStreamOut xsOut)
{
try
{
xsOut.detach(XStreamOut.DEFAULT_MODE);
}
catch(Exception e)
{
System.out.println("cannot detach from the outbound server: "+xsoutName);
System.out.println(e.getMessage());
e.printStackTrace();
}
}

public static void get_lcrs(XStreamIn xsIn, XStreamOut xsOut)
{
if (null == xsIn)
{
System.out.println("xstreamIn is null");
System.exit(0);
}

if (null == xsOut)
{
System.out.println("xstreamOut is null");
System.exit(0);
}

try
{
while(true)
{
// receive an LCR from outbound server
LCR alcr = xsOut.receiveLCR(XStreamOut.DEFAULT_MODE);

if (xsOut.getBatchStatus() == XStreamOut.EXECUTING) // batch is active
{
assert alcr != null;
// send the LCR to the inbound server
xsIn.sendLCR(alcr, XStreamIn.DEFAULT_MODE);

// also get chunk data for this LCR if any
if (alcr instanceof RowLCR)
{
// receive chunk from outbound then send to inbound
if (((RowLCR)alcr).hasChunkData())
{
ChunkColumnValue chunk = null;
do
{
chunk = xsOut.receiveChunk(XStreamOut.DEFAULT_MODE);
xsIn.sendChunk(chunk, XStreamIn.DEFAULT_MODE);
} while (!chunk.isEndOfRow());
}
}
processedLowPosition = alcr.getPosition();
}
else  // batch is end
{
assert alcr == null;
// flush the network
xsIn.flush(XStreamIn.DEFAULT_MODE);
// get the processed_low_position from inbound server
processedLowPosition =
xsIn.getProcessedLowWatermark();
// update the processed_low_position at oubound server
if (null != processedLowPosition)
xsOut.setProcessedLowWatermark(processedLowPosition,
XStreamOut.DEFAULT_MODE);
}
}
}
catch(Exception e)
{
System.out.println("exception when processing LCRs");
System.out.println(e.getMessage());
e.printStackTrace();
}
}

public static void printHex(byte[] b)
{
for (int i = 0; i < b.length; ++i)
{
System.out.print(
Integer.toHexString((b[i]&0xFF) | 0x100).substring(1,3));
}
System.out.println("");
}
}

B XStream Out Restrictions

This chapter describes restrictions for XStream Out.

This chapter contains these topics:

- Capture Process Restrictions

- Propagation Restrictions

- Outbound Server Restrictions

- XStream Out Rule Restrictions

- XStream Out Rule-Based Transformation Restrictions

- XStream Out Limitations for Extended Data Types

Capture Process Restrictions

This section describes restrictions for capture processes.

This section contains these topics:

- Unsupported Data Types for Capture Processes

- Unsupported Changes for Capture Processes

- Supplemental Logging Data Type Restrictions

- Operational Requirements for Downstream Capture with XStream Out

- Capture Processes Do Not Support Oracle Label Security

Unsupported Data Types for Capture Processes

A capture process does not capture the results of DML changes to columns of the following data types:

- BFILE

- ROWID

- The following user-defined types: varrays, REFs, and nested tables

- The following Oracle-supplied types: ANYTYPE, ANYDATASET, URI types, SDO_TOPO_GEOMETRY, SDO_GEORASTER, and Expression

These data type restrictions pertain to both ordinary (heap-organized) tables and index-organized tables.

Capture processes can capture changes to SecureFiles LOB columns only if the source database compatibility level is set to 11.2.0.0 or higher. Also, capture processes do not support capturing changes resulting from fragment-based operations on SecureFiles LOB columns or capturing changes resulting from SecureFiles archive manager operations.

When a capture process tries to create a row LCR for a DML change to a column of an unsupported data type, the capture process can either ignore the change to the table or raise an error. The behavior of the capture process depends on the setting for the ignore_unsupported_table capture process parameter.

When the capture process ignores the change to the table, it does not capture the change, and it records the table name in the alert log. When the capture process raises an error, it writes the LCR that caused the error into its trace file, raises an ORA-26744 error, and becomes disabled. In either case, modify the rules used by the capture process to avoid recording messages in the alert log or capture process errors. After modifying the capture process's rules, restart the capture process.

Note:

- You can add rules to a negative rule set for a capture process that instruct the capture process to discard changes to tables with columns of unsupported data types.

- Capture processes do not support primary keys that contain object type attributes.

- A capture process raises an error if it attempts to capture an INSERT operation with an APPEND hint if the INSERT operation includes a column of either of the following types: XMLType stored as object relational or XMLType stored as binary XML

See Also:

- "Data Types Captured by a Capture Process"

- "Rules and Rule Sets"

- Oracle Database PL/SQL Packages and Types Reference for more information about the ignore_unsupported_table capture process parameter

- Oracle Database SQL Language Reference for more information about data types

- Oracle Database Utilities for more information about LogMiner restrictions for SecureFiles LOB columns

- Oracle Database Upgrade Guide for information about database compatibility

Unsupported Changes for Capture Processes

This section describes changes that are not supported by capture processes.

This section contains these topics:

- Unsupported Schemas for Capture Processes

- Unsupported Table Types for Capture Processes

- Unsupported DDL Changes for Capture Processes

- Changes Ignored by a Capture Process

- NOLOGGING and UNRECOVERABLE Keywords for SQL Operations

- UNRECOVERABLE Clause for Direct Path Loads

Unsupported Schemas for Capture Processes

By default, a capture process does not capture changes made to the following schemas:

- CTXSYS

- DBSNMP

- DMSYS

- DVSYS

- EXFSYS

- LBACSYS

- MDDATA

- MDSYS

- OLAPSYS

- ORDDATA

- ORDPLUGINS

- ORDSYS

- OUTLN

- SI_INFORMTN_SCHEMA

- SYS

- SYSMAN

- SYSTEM

- WMSYS

- XDB

If the include_objects capture process parameter specifies one or more of these schemas, then the capture process captures changes made to the specified schemas. If the include_objects capture process parameter specifies one or more tables in these schemas, then the capture process captures changes made to the specified tables.

By default, the include_objects capture process parameter is set to NULL. Therefore, the capture process does not capture changes made to these schemas.

See Also:
Oracle Database PL/SQL Packages and Types Reference for more information about the include_objects capture process parameter

Unsupported Table Types for Capture Processes

A capture process cannot capture DML changes made to the following types of tables:

- Temporary tables

- Object tables that include the unsupported data types described in "Unsupported Data Types for Capture Processes"

Note:

- A capture process can capture changes to tables compressed with basic table compression and OLTP table compression only if the compatibility level at both the source database and the capture database is set to 11.2.0.0.0 or higher.

- A capture process can capture changes to tables compressed with hybrid columnar compression if all of the following conditions are met: both the source database and the capture database must be running Oracle Database 11g Release 2 (11.2.0.2), and the compatibility level at both the source database and the capture database is set to 11.2.0.0.0 or higher.

See Also:

- "Data Types Captured by a Capture Process"

- Oracle Database Administrator's Guide for information about compressed tables

Unsupported DDL Changes for Capture Processes

A capture process captures the DDL changes that satisfy its rule sets, except for the following types of DDL changes:

- ALTER DATABASE

- CREATE CONTROLFILE

- CREATE DATABASE

- CREATE PFILE

- CREATE SPFILE

A capture process can capture DDL statements, but not the results of DDL statements, unless the DDL statement is a CREATE TABLE AS SELECT statement. For example, when a capture process captures an ANALYZE statement, it does not capture the statistics generated by the ANALYZE statement. However, when a capture process captures a CREATE TABLE AS SELECT statement, it captures the statement itself and all of the rows selected (as INSERT row LCRs).

Some types of DDL changes that are captured by a capture process cannot be applied by an outbound server. If an outbound server receives a DDL LCR that specifies an operation that cannot be processed, then the outbound server ignores the DDL LCR and records information about it in its trace file.

See Also:
"Rules and Rule Sets"

Changes Ignored by a Capture Process

A capture process ignores the following types of changes:

- The session control statements ALTER SESSION and SET ROLE.

- The system control statement ALTER SYSTEM.

- CALL, EXPLAIN PLAN, and LOCK TABLE statements.

- GRANT statements on views.

- Changes made to a table or schema by online redefinition using the DBMS_REDEFINITION package. Online table redefinition is supported on a table for which a capture process captures changes, but the logical structure of the table before online redefinition must be the same as the logical structure after online redefinition.

- Changes to sequence values. For example, if a user references a NEXTVAL or sets the sequence, then a capture process does not capture changes resulting from these operations. Also, if you share a sequence at multiple databases, then sequence values used for individual rows at these databases might vary.

- Invocations of PL/SQL procedures, which means that a call to a PL/SQL procedure is not captured. However, if a call to a PL/SQL procedure causes changes to database objects, then these changes can be captured by a capture process if the changes satisfy the capture process rule sets.

Note:

- If an Oracle-supplied package related to XML makes changes to database objects, then these changes are not captured by capture processes. See Oracle Database PL/SQL Packages and Types Reference for information about packages related to XML.

- If an Oracle-supplied package related to Oracle Text makes changes to database objects, then these changes are not captured by capture processes. See Oracle Text Reference for information about packages related to Oracle Text.

See Also:
Oracle Streams Replication Administrator's Guide for information about strategies to avoid having the same sequence-generated value for two different rows at different databases

NOLOGGING and UNRECOVERABLE Keywords for SQL Operations

If you use the NOLOGGING or UNRECOVERABLE keyword for a SQL operation, then the changes resulting from the SQL operation cannot be captured by a capture process. Therefore, do not use these keywords to capture the changes that result from a SQL operation.

If the object for which you are specifying the logging attributes resides in a database or tablespace in FORCE LOGGING mode, then Oracle Database ignores any NOLOGGING or UNRECOVERABLE setting until the database or tablespace is taken out of FORCE LOGGING mode. You can determine the current logging mode for a database by querying the FORCE_LOGGING column in the V$DATABASE dynamic performance view. You can determine the current logging mode for a tablespace by querying the FORCE_LOGGING column in the ALL_TABLESPACES static data dictionary view.

Note:
The UNRECOVERABLE keyword is deprecated and has been replaced with the NOLOGGING keyword in the logging_clause. Although UNRECOVERABLE is supported for backward compatibility, Oracle strongly recommends that you use the NOLOGGING keyword, when appropriate.

See Also:
Oracle Database SQL Language Reference for more information about the NOLOGGING and UNRECOVERABLE keywords, FORCE LOGGING mode, and the logging_clause

UNRECOVERABLE Clause for Direct Path Loads

If you use the UNRECOVERABLE clause in the SQL*Loader control file for a direct path load, then a capture process cannot capture the changes resulting from the direct path load. Therefore, if the changes resulting from a direct path load should be captured by a capture process, then do not use the UNRECOVERABLE clause.

If you load objects into a database or tablespace that is in FORCE LOGGING mode, then Oracle Database ignores any UNRECOVERABLE clause during a direct path load, and the loaded changes are logged. You can determine the current logging mode for a database by querying the FORCE_LOGGING column in the V$DATABASE dynamic performance view. You can determine the current logging mode for a tablespace by querying the FORCE_LOGGING column in the DBA_TABLESPACES static data dictionary view.

See Also:
Oracle Database Utilities for information about direct path loads and SQL*Loader

Supplemental Logging Data Type Restrictions

Columns of the following data types cannot be part of a supplemental log group: LOB, LONG, LONG RAW, user-defined types (including object types, REFs, varrays, nested tables), and Oracle-supplied types (including Any types, XML types, spatial types, and media types).

See Also:

- "If Required, Configure Supplemental Logging"

- Oracle Database SQL Language Reference for information about data types

Operational Requirements for Downstream Capture with XStream Out

The following are operational requirements for using downstream capture:

- The source database must be running at least Oracle Database 10g Release 2 (10.2).

- The downstream database must be running Oracle Database 11g Release 2 (11.2.0.3) or later and the source database must be running Oracle Database 10g Release 2 (10.2) or later.

- The operating system on the source and downstream capture sites must be the same, but the operating system release does not need to be the same. In addition, the downstream sites can use a different directory structure than the source site.

- The hardware architecture on the source and downstream capture sites must be the same. For example, a downstream capture configuration with a source database on a 64-bit Sun system must have a downstream database that is configured on a 64-bit Sun system. Other hardware elements, such as the number of CPUs, memory size, and storage configuration, can be different between the source and downstream sites.

See Also:
"Local Capture and Downstream Capture"

Capture Processes Do Not Support Oracle Label Security

Capture processes do not support database objects that use Oracle Label Security (OLS).

See Also:
Oracle Label Security Administrator's Guide

Propagation Restrictions

This section describes restrictions for propagations.

This section contains these topics:

- Connection Qualifiers and Propagations

Connection Qualifiers and Propagations

Connection qualifiers cannot be specified in the database links that are used by propagations.

Outbound Server Restrictions

This section describes restrictions for outbound servers.

This section contains these topics:

- Unsupported Data Types for Outbound Servers

- Types of DDL Changes Ignored by an Outbound Server

- Apply Process Features That Are Not Applicable to Outbound Servers

Unsupported Data Types for Outbound Servers

An outbound server does not process row LCRs containing the results of DML changes in columns of the following data types:

- BFILE

- ROWID

- The following user-defined types: varrays, REFs, and nested tables

- The following Oracle-supplied types: ANYTYPE, ANYDATASET, URI types, SDO_TOPO_GEOMETRY, SDO_GEORASTER, and Expression

An outbound server raises an error if it attempts to process a row LCR that contains information about a column of an unsupported data type. In addition, an outbound server cannot process DML changes to the following types of tables:

- Temporary tables

- Object tables that include unsupported data types

An outbound server raises an error if it attempts to process such changes. When an outbound server raises an error for an LCR, it moves the transaction that includes the LCR into the error queue.

See Also:

- "Data Types Supported by Outbound Servers"

- Oracle Database SQL Language Reference for information about data types

Types of DDL Changes Ignored by an Outbound Server

The following types of DDL changes are not supported by an outbound server:

- ALTER MATERIALIZED VIEW

- ALTER MATERIALIZED VIEW LOG

- CREATE DATABASE LINK

- CREATE SCHEMA AUTHORIZATION

- CREATE MATERIALIZED VIEW

- CREATE MATERIALIZED VIEW LOG

- DROP DATABASE LINK

- DROP MATERIALIZED VIEW

- DROP MATERIALIZED VIEW LOG

- FLASHBACK DATABASE

- RENAME

If an outbound server receives a DDL LCR that specifies an operation that cannot be processed, then the outbound server ignores the DDL LCR and records the following message in the outbound server trace file, followed by the DDL text that was ignored:

Apply process ignored the following DDL:

An outbound server applies all other types of DDL changes if the DDL LCRs containing the changes should be applied according to the outbound server rule sets.

Note:

- An outbound server processes ALTER object_type object_name RENAME changes, such as ALTER TABLE jobs RENAME. Therefore, if you want DDL changes that rename objects to be processed, then use ALTER object_type object_name RENAME statements instead of RENAME statements.

- The name "materialized view" is synonymous with the name "snapshot". Snapshot equivalents of the statements on materialized views are ignored by an outbound server.

See Also:
"Rules and Rule Sets"

Apply Process Features That Are Not Applicable to Outbound Servers

The following apply process features cannot be used with outbound servers:

- Apply handlers
You cannot specify an apply handler for an outbound server. The client application can perform custom processing of the LCRs instead if necessary. However, if apply processes are configured in the same database as the outbound server, then you can specify apply handlers for these apply processes. In addition, you can configure general apply handlers for the database. An outbound server ignores general apply handlers.

See Oracle Streams Concepts and Administration.

- The following apply parameters:

- allow_duplicate_rows

- commit_serialization

- compare_key_only

- disable_on_error

- parallelism

- preserve_encryption

- rtrim_on_implicit_conversion

Outbound servers ignore the settings for these apply parameters.

The commit_serialization parameter is always set to FULL for an outbound server, and the parallelism parameter is always set to 1 for an outbound server.

See Oracle Database PL/SQL Packages and Types Reference.

- Apply tags
An outbound server cannot set an apply tag for the changes it processes.

See Oracle Streams Replication Administrator's Guide.

- Apply database links
Outbound servers cannot use database links.

See Oracle Streams Replication Administrator's Guide.

- Conflict detection and resolution
An outbound server does not detect conflicts, and conflict resolution cannot be set for an outbound server.

See Oracle Streams Replication Administrator's Guide.

- Dependency scheduling
An outbound server does not evaluate dependencies because its parallelism must be 1.

See Oracle Streams Concepts and Administration.

- Substitute key column settings
An outbound server ignores substitute key column settings.

See Oracle Streams Concepts and Administration.

- Enqueue directives specified by the SET_ENQUEUE_DESTINATION procedure in the DBMS_APPLY_ADM package
An outbound server cannot enqueue changes into an Oracle database queue automatically using the SET_ENQUEUE_DESTINATION procedure.

See Oracle Database PL/SQL Packages and Types Reference.

- Execute directives specified by the SET_EXECUTE procedure in the DBMS_APPLY_ADM package
An outbound server ignores execute directives.

See Oracle Database PL/SQL Packages and Types Reference.

- Error creation and execution
An outbound server does not create an error transaction when it encounters an error. It records information about errors in the ALL_APPLY view, but it does not enqueue the transaction into an error queue.

See Oracle Streams Concepts and Administration.

XStream Out Rule Restrictions

This section describes restrictions for rules.

Restrictions for Subset Rules

The following restrictions apply to subset rules:

- A table with the table name referenced in the subset rule must exist in the same database as the subset rule, and this table must be in the same schema referenced for the table in the subset rule.

- If the subset rule is in the positive rule set for a capture process, then the table must contain the columns specified in the subset condition, and the data type of each of these columns must match the data type of the corresponding column at the source database.

- If the subset rule is in the positive rule set for a propagation, then the table must contain the columns specified in the subset condition, and the data type of each column must match the data type of the corresponding column in row LCRs that evaluate to TRUE for the subset rule.

- Creating subset rules for tables that have one or more columns of the following data types is not supported: LOB, LONG, LONG RAW, user-defined types (including object types, REFs, varrays, nested tables), and Oracle-supplied types (including Any types, XML types, spatial types, and media types).

See Also:

- "Subset Rules"

- Oracle Database SQL Language Reference for more information about data types

XStream Out Rule-Based Transformation Restrictions

This section describes restrictions for rule-based transformations.

See Also:
"Rule-Based Transformations"

Unsupported Data Types for Declarative Rule-Based Transformations

Except for add column transformations, declarative rule-based transformations that operate on columns support the same data types that are supported by capture processes.

Add column transformations cannot add columns of the following data types: BLOB, CLOB, NCLOB, BFILE, LONG, LONG RAW, ROWID, user-defined types (including object types, REFs, varrays, nested tables), and Oracle-supplied types (including Any types, XML types, spatial types, and media types).

Extended data type columns cannot be used in the following types of declarative rule-based transformations:

- Add column

- Keep columns

See Also:

- "Data Types Captured by a Capture Process"

- "Unsupported Data Types for Capture Processes"

- "XStream Out Limitations for Extended Data Types"

- Oracle Database SQL Language Reference for information about data types

XStream Out Limitations for Extended Data Types

The maximum size of the VARCHAR2, NVARCHAR2, and RAW data types has been increased in Oracle Database 12c when the COMPATIBLE initialization parameter is set to 12.0.0 and the MAX_STRING_SIZE initialization parameter is set to EXTENDED. XStream Out supports these extended data types.

However, the following limitations apply to the extended data type:

- Information about an extended data type column might not be contained in the original LCR for a data manipulation language (DML) operation. Instead, XStream Out might treat the extended data type column similar to the way it treats LOB columns. Specifically, additional LCRs might contain the information for the extended data type column.

- XStream rules cannot access data in LCRs for extended data type columns.

- Extended data type columns cannot be specified in a subset rule clause.

- Extended data type columns cannot be used in the following types of declarative rule-based transformations:

- Add column

- Keep columns

See Also:
Oracle Database SQL Language Reference for more information about extended data types

C XStream In Restrictions

This chapter describes restrictions for XStream In.

This chapter contains these topics:

- Inbound Server Restrictions

- XStream In Rule Restrictions

- XStream In Rule-Based Transformation Restrictions

- XStream In Limitations for Extended Data Types

Inbound Server Restrictions

This section describes restrictions for inbound servers.

This section contains these topics:

- Unsupported Data Types for Inbound Servers

- Unsupported Data Types for Apply Handlers

- Types of DDL Changes Ignored by an Inbound Server

- Current Schema User Must Exist at Destination Database

- Inbound Servers Do Not Support Oracle Label Security

Unsupported Data Types for Inbound Servers

An inbound server does not apply row LCRs containing the results of DML changes in columns of the following data types:

- BFILE

- ROWID

- The following user-defined types: varrays, REFs, and nested tables

- The following Oracle-supplied types: ANYTYPE, ANYDATASET, URI types, SDO_TOPO_GEOMETRY, SDO_GEORASTER, and Expression.

An inbound server raises an error if it attempts to apply a row LCR that contains information about a column of an unsupported data type. In addition, an inbound server cannot apply DML changes to the following types of tables:

- Temporary tables

- Object tables that include unsupported data types

An inbound server raises an error if it attempts to apply such changes. When an inbound server raises an error for an LCR, it moves the transaction that includes the LCR into the error queue.

These data type restrictions pertain to both ordinary (heap-organized) tables and index-organized tables.

See Also:

- "Data Types Applied by Inbound Servers"

- Oracle Database SQL Language Reference for information about data types

Unsupported Data Types for Apply Handlers

Statement DML handlers cannot process LONG, LONG RAW, or nonassembled LOB column data in row LCRs. However, statement DML handlers can process LOB column data in row LCRs that have been constructed by LOB assembly. LOB assembly is enabled by default for statement DML handlers.

Procedure DML handlers and error handlers cannot process LONG or LONG RAW column data in row LCRs. However, procedure DML handlers and error handlers can process both nonassembled and assembled LOB column data in row LCRs, but these handlers cannot modify nonassembled LOB column data.

See Also:

- "LCR Processing Options for Inbound Servers"

- Oracle Streams Replication Administrator's Guide for information about LOB assembly

- Oracle Database SQL Language Reference for more information about data types

Types of DDL Changes Ignored by an Inbound Server

The following types of DDL changes are not supported by an inbound server. These types of DDL changes are not applied:

- ALTER MATERIALIZED VIEW

- ALTER MATERIALIZED VIEW LOG

- CREATE DATABASE LINK

- CREATE SCHEMA AUTHORIZATION

- CREATE MATERIALIZED VIEW

- CREATE MATERIALIZED VIEW LOG

- DROP DATABASE LINK

- DROP MATERIALIZED VIEW

- DROP MATERIALIZED VIEW LOG

- FLASHBACK DATABASE

- RENAME

If an inbound server receives a DDL LCR that specifies an operation that cannot be applied, then the inbound server ignores the DDL LCR and records the following message in the inbound server trace file, followed by the DDL text that was ignored:

Inbound server ignored the following DDL:

An inbound server applies all other types of DDL changes if the DDL LCRs containing the changes should be applied according to the inbound server rule sets.

Note:

- An inbound server applies ALTER object_type object_name RENAME changes, such as ALTER TABLE jobs RENAME. Therefore, if you want DDL changes that rename objects to be applied, then use ALTER object_type object_name RENAME statements instead of RENAME statements. After changing the name of a database object, new rules that specify the new database object name might be needed to replicate changes to the database object.

- The name "materialized view" is synonymous with the name "snapshot". Snapshot equivalents of the statements on materialized views are ignored by an inbound server.

See Also:
"Rules and Rule Sets"

Current Schema User Must Exist at Destination Database

For a DDL LCR to be applied at a destination database successfully, the user specified as the current_schema in the DDL LCR must exist at the destination database. The current schema is the schema that is used if no schema is specified for an object in the DDL text.

See Also:

- Oracle Database Concepts for more information about database structures

- Oracle Database PL/SQL Packages and Types Reference for more information about the current_schema attribute in DDL LCRs

Inbound Servers Do Not Support Oracle Label Security

Inbound servers do not support database objects that use Oracle Label Security (OLS).

See Also:
Oracle Label Security Administrator's Guide

XStream In Rule Restrictions

This section describes XStream In restrictions for rules.

This section contains these topics:

- Restrictions for Subset Rules

Restrictions for Subset Rules

The following restrictions apply to subset rules:

- A table with the table name referenced in the subset rule must exist in the same database as the subset rule, and this table must be in the same schema referenced for the table in the subset rule.

- If the subset rule is in the positive rule set for an inbound server, then the table must contain the columns specified in the subset condition, and the data type of each column must match the data type of the corresponding column in row LCRs that evaluate to TRUE for the subset rule.

- Creating subset rules for tables that have one or more columns of the following data types is not supported: LOB, LONG, LONG RAW, user-defined types (including object types, REFs, varrays, nested tables), and Oracle-supplied types (including Any types, XML types, spatial types, and media types).

See Also:

- "Subset Rules"

- Oracle Database SQL Language Reference for more information about data types

XStream In Rule-Based Transformation Restrictions

This section describes restrictions for rule-based transformations.

See Also:
"Rule-Based Transformations"

Unsupported Data Types for Declarative Rule-Based Transformations

Except for add column transformations, declarative rule-based transformations that operate on columns support the same data types that are supported by inbound servers.

Add column transformations cannot add columns of the following data types: BLOB, CLOB, NCLOB, BFILE, LONG, LONG RAW, ROWID, user-defined types (including object types, REFs, varrays, nested tables), and Oracle-supplied types (including Any types, XML types, spatial types, and media types).

See Also:

- "Data Types Applied by Inbound Servers"

- "Unsupported Data Types for Inbound Servers"

- Oracle Database SQL Language Reference for information about data types

XStream In Limitations for Extended Data Types

The maximum size of the VARCHAR2, NVARCHAR2, and RAW data types has been increased in Oracle Database 12c when the COMPATIBLE initialization parameter is set to 12.0.0 and the MAX_STRING_SIZE initialization parameter is set to EXTENDED. XStream In supports these extended data types.

However, the following limitations apply to the extended data types:

- Information about an extended data type column might not be contained in the original LCR for a data manipulation language (DML) operation. Instead, XStream In might treat the extended data type column similar to the way it treats LOB columns. Specifically, additional LCRs might contain the information for the extended data type column.

- XStream rules cannot access data in LCRs for extended data type columns.

- Extended data type columns cannot be specified in a subset rule clause.

- Extended data type columns cannot be used for conflict detection.

- Extended data type columns cannot be used for a substitute primary key for apply purposes with the DBMS_APPLY_ADM.SET_KEY_COLUMNS procedure.

- Extended data type columns cannot be used in the following types of declarative rule-based transformations:

- Add column

- Keep columns

See Also:
Oracle Database SQL Language Reference for more information about extended data types

Index
A  B  C  D  E  F  G  I  K  L  M  N  O  P  Q  R  S  T  U  V  X

A

ADD SUPPLEMENTAL LOG, 4.1.2.7.2

ADD SUPPLEMENTAL LOG DATA, 4.1.2.7.3

ADD SUPPLEMENTAL LOG DATA clause of ALTER DATABASE, 4.1.2.7.5

ADD SUPPLEMENTAL LOG GROUP clause of ALTER TABLE

conditional log groups, 4.1.2.7.3

unconditional log groups, 4.1.2.7.2

ADD_OUTBOUND procedure, 4.2.3, 4.2.4.2 ADD_SUBSET_OUTBOUND_RULES procedure, 5.4.1.2 ADD_TABLE_RULES procedure, 5.4.1.3 ALL_APPLY view, 6.3.2, 11.3 ALL_APPLY_ERROR view, 11.7.4, 11.7.5 ALL_CAPTURE_EXTRA_ATTRIBUTES view, 7.2.4 ALL_PROPAGATION view, 12.2.1 ALL_XSTREAM_INBOUND view, 11.2 ALL_XSTREAM_INBOUND_PROGRESS view, 11.5 ALL_XSTREAM_OUTBOUND view, 5.3.1, 6.3.1 ALL_XSTREAM_OUTBOUND_PROGRESS view, 6.3.5 ALTER DATABASE statement

ADD SUPPLEMENTAL LOG DATA clause, 4.1.2.7.5

DROP SUPPLEMENTAL LOG DATA clause, 4.1.2.7.6

ALTER TABLE statement

ADD SUPPLEMENTAL LOG DATA clause

conditional log groups, 4.1.2.7.3

unconditional log groups, 4.1.2.7.2

ADD SUPPLEMENTAL LOG GROUP clause

conditional log groups, 4.1.2.7.3

unconditional log groups, 4.1.2.7.2

DROP SUPPLEMENTAL LOG GROUP clause, 4.1.2.7.4 ALTER_INBOUND procedure, 10.5 ALTER_OUTBOUND procedure, 5.2.4, 5.4.1.1, 5.4.2.1 apply handlers, 8.1

outbound servers, B.3.3

apply process

Oracle Real Application Clusters, 3.7.1.4

trace files, 7.1.3.3

apply user, 3.3.3

XStream In, 10.5

ARCHIVELOG mode

capture process

Recovery Manager, 3.7.4

XStream Out, 4.1.2.4

B

buffered queues

Transparent Data Encryption, 3.7.2.3

C

capture process, 3.3

changes captured

DDL changes, B.1.2.3

NOLOGGING keyword, B.1.2.5

UNRECOVERABLE clause for SQL*Loader, B.1.2.6

UNRECOVERABLE SQL keyword, B.1.2.5

checkpoint retention time, 3.2.9.3 checkpoints, 3.2.9 fast recovery area, 3.7.4 maximum checkpoint SCN, 3.2.9.2 online redefinition, B.1.2.4 Oracle Label Security (OLS), B.1.5 Oracle Real Application Clusters, 3.7.1.1 Recovery Manager, 3.7.4 required checkpoint SCN, 3.2.9.1 schema restrictions, B.1.2.1 supplemental logging, 4.1.2.7 table type restrictions, B.1.2.2 trace files, 7.1.3.1 Transparent Data Encryption, 3.7.2.1 CDBs

XStream In, 8.6.4

XStream Out, 3.7.6

configuring, 4.2.4.1

configuring multiple, 4.2.4.2

character sets

SQL generation, 2.5.3

checkpoint retention time, 3.2.9.3 checkpoints, 3.2.9 client applications

XStream

example, A.1

commit_scn_from_position LCR attribute, 3.4.1 conflict resolution, 8.1

outbound server, B.3.3

connect user, 3.6.4 CREATE_INBOUND procedure, 9.2 CREATE_OUTBOUND procedure, 4.2.1

D

data types

SQL generation, 2.5.3

database links

XStream Out, 4.1.2.3

demos

file-based replication, 1.3.2.1

ID key LCRs, 3.2.2.1.1

SQL generation, 2.5.6

XStream, A.1

dependency scheduling

outbound servers, B.3.3

direct path load

capture processes, B.1.2.6

distributed transactions

XStream Out, 3.5

DROP SUPPLEMENTAL LOG DATA clause of ALTER DATABASE, 4.1.2.7.6 DROP SUPPLEMENTAL LOG GROUP clause, 4.1.2.7.4 DROP_INBOUND procedure, 10.7 DROP_OUTBOUND procedure, 5.6

E

eager errors, 10.6.3

eager_size apply parameter, 8.4.1

F

fast recovery area

capture processes, 3.7.4

flashback data archive

XStream In, 8.6.2

XStream Out, 3.7.3

G

GET_COMMA, 11.7.3

GET_DDL_TEXT member function, 11.7.3

GET_ERROR_MESSAGE function, 11.7.4, 11.7.5

GET_OBJECT_NAME member function, 11.7.3

GET_OBJECT_OWNER member function, 11.7.3

GET_SOURCE_DATABASE_NAME member function, 11.7.3

GET_VALUES member function, 11.7.3

I

ID key LCRs, 3.2.2.1

demo, 3.2.2.1.1

inbound server

data types, C.1.1

large transactions, 8.4.1

inbound servers, 8.2

applied high position, 8.3

applied low position, 8.3

apply user, 8.5

changing, 10.5

configuring, 9.2 DDL changes

current schema, C.1.4

ignored, C.1.3

dropping, 10.7 eager errors, 10.6.3 Oracle Label Security (OLS), C.1.5 positions, 8.3

monitoring, 11.5

preparing for, 9.1 processed low position, 8.3 spill position, 8.3 INCLUDE_EXTRA_ATTRIBUTE procedure, 7.2.4 initialization parameters

XStream In, 9.1.2

XStream Out, 4.1.2.5, 4.1.2.5

instantiation system change number, 3.3.6 IS_NULL_TAG member function, 11.7.3

K

keystores

XStream Out, 3.7.2.3

L

last sent position

monitoring, 6.3.3

logical change records (LCRs), 1.1

commit_scn_from_position attribute, 3.4.1

DDL LCRs

current_schema, C.1.4

getting information about, 11.7.3 ID key LCRs, 3.2.2.1 missing, 7.2.2 missing attributes, 7.2.4 scn_from_position attribute, 3.4.1 sequence LCRs, 2.1.4

M

max_parallelism apply parameter, 8.4.1

maximum checkpoint SCN, 3.2.9.2

multitenant architecture

XStream In, 8.6.4

XStream Out, 3.7.6

N

NOLOGGING mode

capture process, B.1.2.5

O

OCIXStreamOutAttach(), 7.2.1

online redefinition

capture process, B.1.2.4

ORA-03135 error, 12.2.2 Oracle Label Security (OLS)

capture processes, B.1.5

inbound servers, C.1.5

Oracle Real Application Clusters

interoperation with Oracle Streams, 3.7.1.1

interoperation with XStream In, 8.6.1

interoperation with XStream Out, 3.7.1.2, 3.7.1.4

queues, 3.7.1.2

Oracle Streams, 1.1

queues

Oracle Real Application Clusters, 3.7.1.2

Oracle Streams Performance Advisor

XStream, 2.4

outbound servers, 3.3

apply handlers, B.3.3

apply user, 3.3.3

capture processes, 3.3

configuration options, 4.1.1

configuring, 4.2

conflict resolution, B.3.3

connect user, 3.6, 3.6.4

changing, 5.2.4

data types, B.3.1 DDL changes

ignored, B.3.2

dependency scheduling, B.3.3 dropping, 5.6 monitoring, 6.3 preparing for, 4.1 processed low position, 3.4.2

monitoring, 6.3.5

rules

adding, 5.4.1

removing, 5.4.2

SET_ENQUEUE_DESTINATION procedure, B.3.3 SET_EXECUTE procedure, B.3.3 statistics

monitoring, 6.3.4

streaming network transmission, 3.4.3 substitute key columns, B.3.3 tags, B.3.3 transactions

monitoring, 6.3.3

P

PDBs

XStream In, 8.6.4

XStream Out, 3.7.6

configuring, 4.2.4.1

positions

applied high position, 8.3, 11.5

applied low position, 8.3, 11.5

processed low position, 3.4.2, 6.3.5, 8.3, 11.5

spill position, 8.3, 11.5

XStream, 2.1.5

XStream In, 8.3

monitoring, 11.5

XStream Out, 3.4 processed low position, 3.4.2

monitoring, 6.3.5

propagation, 3.3.1 propagations

queue-to-queue

Oracle Real Application Clusters, 3.7.1.2

Transparent Data Encryption, 3.7.2.2

Q

queues

Oracle Real Application Clusters, 3.7.1.2

R

Recovery Manager

capture processes

archived redo log files, 3.7.4

REMOVE_RULE procedure, 5.4.2.3 REMOVE_SUBSET_OUTBOUND_RULES procedure, 5.4.2.2 REMOVE_XSTREAM_ADM procedure, 5.7 replication

configuring

supplemental logging, 4.1.2.7

XStream, 1.3.1 required checkpoint SCN, 3.2.9.1 restrictions

XStream In, C

XStream Out, B

rule-based transformations, 1.1, 7.2.2, 8.1

restrictions, B.5

rules, 1.1, 8.1

restrictions, B.4

XStream

monitoring, 6.5

XStream Out, 5.4

custom conditions, 5.4.1.3

S

scn_from_position LCR attribute, 3.4.1

security

trusted user model, 1.5

untrusted user model, 1.5

XStream In, 8.5

component-level, 8.5.2

XStream Out, 3.6

client, 3.6.1

component-level, 3.6.2

sequence LCRs, 2.1.4 SET_ENQUEUE_DESTINATION procedure

outbound servers, B.3.3

SET_EXECUTE procedure

outbound servers, B.3.3

SET_MESSAGE_TRACKING procedure, 7.2.2 SET_TRIGGER_FIRING_PROPERTY procedure, 8.2.6 source database, 3.3 split and merge, 3.3.6 SQL generation

character sets, 2.5.4

data types, 2.5.3

examples, 2.5.5

XStream, 2.5

character sets, 2.5.3

demo, 2.5.6

formats, 2.5.2

interfaces, 2.5.1

SQL*Loader

capture processes, B.1.2.6

statistics

XStream Out, 6.3.4

Streams pool, 7.2.5

XStream In, 9.1.3

XStream Out, 4.1.2.6

substitute key columns

outbound servers, B.3.3

supplemental logging, 4.1.2.7

T

tags

outbound server, B.3.3

Transparent Data Encryption

buffered queues, 3.7.2.3

capture processes, 3.7.2.1

propagations, 3.7.2.2

transportable tablespaces

interoperation with XStream In, 8.6.3

triggers

XStream In, 8.2.6

troubleshooting

XStream, 7, 12

U

UNRECOVERABLE clause

SQL*Loader

capture process, B.1.2.6

UNRECOVERABLE SQL keyword

capture process, B.1.2.5

UTL_SPADV package

XStream, 2.4.4

V

V$PROPAGATION_RECEIVER view, 7.2.5

V$SESSION view, 6.2

V$STREAMS_CAPTURE view, 7.2.5

V$STREAMS_POOL_STATISTICS view, 7.2.5

V$XSTREAM_CAPTURE view, 7.2.2

V$XSTREAM_OUTBOUND_SERVER view, 6.3.3, 6.3.4, 6.3.6

X

XA interface, 3.5

XStream

client applications

example, A.1

configuring, 4, 9, A demos, A.1 diagnosing problems, 7.1, 12.1 managing, 5, 10

overview, 5.1

monitoring, 6, 11

outbound servers, 6.3

rules, 6.5

Oracle Streams Performance Advisor, 2.4 positions, 2.1.5 security, 3.6, 8.5 session information, 6.2 SQL generation, 2.5 troubleshooting, 7, 12

client application, 7.2.1, 7.2.5

inbound servers, 12.2.1

missing LCR attributes, 7.2.4

missing LCRs, 7.2.2

ORA-03135 error, 12.2.2

use cases, 1.3

replication, 1.3.1

sharing data in files, 1.3.2

UTL_SPADV package, 2.4.4 XStream In

applied high position, 8.3

applied low position, 8.3

apply user, 10.5

configuring, 9.2

eager errors, 10.6.3

inbound servers, 8.2

initialization parameters, 9.1.2

position, 11.5

positions, 8.3

preparing for, 9.1

processed low position, 8.3

spill position, 8.3

Streams pool, 9.1.3

triggers, 8.2.6

XStream Out, 3.1

ARCHIVELOG mode, 4.1.2.4

configuration options, 4.1.1

configuring, 4.2

database links, 4.1.2.3

distributed transactions, 3.5

dropping components, 5.6, 10.7

ID key LCRs, 3.2.2.1

initialization parameters, 4.1.2.5, 4.1.2.5

monitoring, 6.3

outbound servers, 3.3

positions, 3.4

preparing for, 4.1

process, 6.3.6

processed low position, 3.4.2, 6.3.5

rules, 5.4

sequence LCRs, 2.1.4

statistics, 6.3.4

streaming network transmission, 3.4.3

Streams pool, 4.1.2.6

transactions, 6.3.3

XStream In, 8

flashback data archive, 8.6.2

interoperation with Oracle Real Application Clusters, 8.6.1

interoperation with transportable tablespaces, 8.6.3

large transactions, 8.4.1

restrictions, C

XStream Out, 3

flashback data archive, 3.7.3

propagation

Oracle Real Application Clusters, 3.7.1.2

removing configuration, 5.7 restrictions, B rule restrictions, B.4 rule-based transformation restrictions, B.5 staging

Oracle Real Application Clusters, 3.7.1.2

Transparent Data Encryption, 3.7.2.3

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