Preface

This manual describes implementation issues for an Oracle8i distributed database system. It also introduces the tools and utilities available to assist you in implementing and maintaining your distributed system.

Oracle8i Distributed Database Systems contains information that describes the features and functionality of the Oracle8i and the Oracle8i Enterprise Edition products. Oracle8i and Oracle8i Enterprise Edition have the same basic features, but several advanced features are available only with the Enterprise Edition, and some of these are optional.

See Also: Getting to Know Oracle8i for information about the differences between Oracle8i and the Oracle8i Enterprise Edition.

What's New in Oracle8i?

This section describes new features in Oracle8i.

Release 8.1.6

The following distributed database features are new in release 8.1.6:

• Oracle now enables generic connectivity to heterogeneous systems through ODBC and OLE DB standards. See:
  • Chapter 8, "Managing Heterogeneous Services Using Generic Connectivity"

  • Appendix C, "Data Dictionary Translation for Generic Connectivity"

  • Appendix D, "Datatype Mapping"

  For transparent gateways, Oracle supports and certifies the configuration from the Oracle application tools to the target system. For generic connectivity, Oracle supports the HS ODBC agent--for any issues with non-Oracle components you should contact appropriate vendors.

• Oracle8i supports functionality that allows a global user to be centrally managed by an enterprise directory (see "Centralized User and Privilege Management"). Consequently, the administrator of each database is not required to create a new schema for each new global user in the distributed system. The central LDAP-based directory contains information about:
  • Which databases in a distributed system an enterprise user can access

  • Which role on each database an enterprise user can use

  • Which schema on each database an enterprise user can connect to

• You can execute DML and DDL statements in parallel, and INSERT direct load statements serially (see "DML and DDL Transactions").

• The Kerberos authentication tool works with connected user database links (see "Distributed Database Security").

• As part of the Oracle Advanced Security option, SSL (single sign-on) allows users to connect to multiple databases without repeatedly typing in passwords (see "Distributed Database Security")

• The following Heterogeneous Services initialization parameters are new for release 8.1.6:
  • HS_FDS_CONNECT_INFO

  • HS_FDS_SHAREABLE_NAME

  • HS_FDS_TRACE

  • HS_FDS_TRACE_FILE_NAME

Release 8.1.5

The following distributed database features are new in release 8.1.5:

• The distributed SQL optimization capabilities of the Oracle server are extended to account for non-Oracle systems. This extension means that Oracle determines the best method for executing the SQL statement. For example, Oracle may determine that the greatest distributed performance can be achieved by performing a join at the remote non-Oracle site. In this case, only the rows that satisfy the SELECT statement are returned to the originating Oracle site, greatly reducing the amount of data transmitted through the network. Additionally, collocated in-line views can improve the performance of a distributed query by accessing multiple tables of a non-Oracle system at once, thereby reducing the number of round trips.

• The following heterogeneous services views are new (see "Using the Heterogeneous Services Dynamic Performance Views"):
  • V$HS_AGENT

  • V$HS_SESSION

Structure

This book contains the following parts and chapters:

Part / Chapter	Contents
PART 1	Distributed Database Systems Concepts and Administration
Chapter 1, "Distributed Database Concepts"	Describes the basic concepts and terminology of Oracle's distributed database architecture. It is recommended reading for anyone planning to implement or maintain a distributed database system.
Chapter 2, "Managing a Distributed Database"	Discusses issues of concern to the database administrator (DBA) implementing or maintaining distributed databases.
Chapter 3, "Developing Applications for a Distributed Database System"	Describes the special considerations that are necessary if you are designing an application to run in a distributed system.
PART 2	Distributed Transactions Concepts and Administration
Chapter 4, "Distributed Transactions Concepts"	Describes how Oracle maintains the integrity of distributed transactions using the two-phase commit mechanism.
Chapter 5, "Managing Distributed Transactions"	Explains how to administer distributed transactions.
PART 3	Heterogeneous Services Concepts and Administration
Chapter 6, "Oracle Heterogeneous Services Concepts"	Provides an overview of Oracle Heterogeneous Services.
Chapter 7, "Managing Oracle Heterogeneous Services Using Transparent Gateways"	Explains how to implement and maintain Heterogeneous Services using an Oracle Transparent Gateway.
Chapter 8, "Managing Heterogeneous Services Using Generic Connectivity"	Provides the information you need to connect to non-Oracle data stores through ODBC or OLE DB.
Chapter 9, "Developing Applications with Heterogeneous Services"	Provides the information you will need to develop applications that use Oracle Heterogeneous Services.
Appendix A, "Heterogeneous Services Initialization Parameters"	Lists all Heterogeneous Services-specific initialization parameters and their values.
Appendix B, "Data Dictionary Views Available Through Heterogeneous Services"	Lists the data dictionary views that are available through heterogeneous services mapping.
Appendix C, "Data Dictionary Translation for Generic Connectivity"	Lists translations for non-Oracle data dictionary information. Generic connectivity agents translate queries to the Oracle8i data dictionary table into queries that retrieve data from a non-Oracle data dictionary.
Appendix D, "Datatype Mapping"	Lists datatypes mapped from ODBC and OLE DB compliant data sources to supported Oracle datatypes.

Changes to This Book

The following aspects of this manual are new in 8.1.6:

• Chapter 8, "Managing Heterogeneous Services Using Generic Connectivity", Appendix C, "Data Dictionary Translation for Generic Connectivity", and Appendix D, "Datatype Mapping" describe generic connectivity.

• The distributed transactions documentation now constitutes its own Part of the book.

• Heterogeneous packages are now documented in Oracle8i Supplied PL/SQL Packages Reference rather than in the appendices of this manual.

Audience

This guide is for DBAs who administer or plan to implement a distributed database system involving either Oracle to Oracle database links or Oracle to non-Oracle database links.

Knowledge Assumed of the Reader

Readers of this guide are assumed to be familiar with:

• Relational database concepts and basic database administration as described in Oracle8i Concepts and the Oracle8i Administrator's Guide.

• The operating system environment under which they are running Oracle.

How to Use This Guide

This manual contains these basic types of information:

Information Type	Chapter
Conceptual	Chapter 1, "Distributed Database Concepts" Chapter 4, "Distributed Transactions Concepts" Chapter 6, "Oracle Heterogeneous Services Concepts"
Administrative	Chapter 2, "Managing a Distributed Database" Chapter 7, "Managing Oracle Heterogeneous Services Using Transparent Gateways" Chapter 8, "Managing Heterogeneous Services Using Generic Connectivity"
Application Development	Chapter 3, "Developing Applications for a Distributed Database System" Chapter 9, "Developing Applications with Heterogeneous Services"
Reference	Appendix A, "Heterogeneous Services Initialization Parameters" Appendix B, "Data Dictionary Views Available Through Heterogeneous Services" Appendix C, "Data Dictionary Translation for Generic Connectivity" Appendix D, "Datatype Mapping"

To acquaint yourself with the basic features of distributed databases in homogeneous and heterogeneous systems, read Chapter 1, "Distributed Database Concepts" and then Chapter 6, "Oracle Heterogeneous Services Concepts".

Refer to the administrative chapters to learn how to perform specific tasks related to management of distributed systems. Refer to the application development chapters if your interest is in designing application that work with distributed systems. Finally, refer to the reference chapters for information about heterogeneous services initialization parameters and generic connectivity mapping.

Conventions Used in This Guide

The following conventions are used in code fragments in this guide:

Format	Indicates
UPPERCASE TEXT	Text that must be entered exactly as shown. For example: SQLPLUS username/password INTO TABLENAME `table`
lowercase italicized text	Emphasized term or glossary term. It also identifies a variable for which you should substitute an appropriate value. Parentheses should be entered as shown. For example: VARCHAR (length)
Vertical bars |	Alternate choices. For example: ASC | DESC
Braces { }	The enclosed items are required, that is, you must choose one of the alternatives. For example: {column_name | array_def}
Square brackets [ ]	The enclosed items are optional. For example: DECIMAL (digits [ , precision ])
<operator>	A SQL operator. For example: WHERE x <operator> x
Ellipses ...	A repeated item. For example: WHERE column_1 <operator> x AND column_2 <operator> y [AND ...]

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