Oracle9i Replication Release 1 (9.0.1) Part Number A87499-02 |
|
This section describes the new replication features of Oracle9i release 9.0. New features information from previous releases is also retained to help those users migrating or upgrading to the current release.
The following sections describe the new features in replication:
The Oracle9i release 9.0 replication features and enhancements are described in the following sections. Oracle9i extends availability by reducing the need to quiesce the replication environment. Replication sites can remain open to users while certain database administration operations are taking place. Oracle9i also enables you to replicate user-defined types and create materialized views that are based on other materialized views. In addition, you can fast refresh more types of materialized views in Oracle9i.
Oracle Replication extends the availability of your replication databases by reducing the number of operations that require quiesce of a master group. The tables in your master group can continue to process transactions while these administration operations are taking place.
Quiescing means stopping all replication activity for a master group. When a master group is quiesced, users cannot perform data manipulation language (DML) statements on any of the tables in the master group. Also, all deferred transactions must be propagated before you can quiesce a master group.
The following sections describe operations that no longer require quiesce in release 9.0. In these sections, the replication management API procedures that correspond to each operation are listed.
You can add new master sites to a master group without quiescing the group. Use the following procedures in the DBMS_REPCAT
package to complete this operation:
You can use the ALTER_MASTER_REPOBJECT
procedure in the DBMS_REPCAT
package to make safe changes to a replicated object in a single master environment. Quiesce is still required for these changes in a multimaster environment.
See Also:
Oracle9i Replication Management API Reference for detailed information about using the procedures described previously in this section |
You can replicate user-defined types and the database objects that are based on them in both a multimaster replication environment and a materialized view replication environment. The database objects that you can replicate include:
REF
columns
Oracle9i also supports replication of multilevel collections.
The multitier materialized view feature enables you to create a materialized view that is based on another materialized view, instead of on a master table at a master site. These materialized views function in the same way as materialized views that are based on master tables, and they can be read-only or updatable.
Performance improvements make refreshing materialized views faster in release 9.0. Also, release 9.0 extends fast refresh capabilities for materialized views by enabling you to fast refresh the following types of materialized views:
Some restrictions apply.
The following are new dynamic performance views for performance monitoring:
V$MVREFRESH
contains information about local materialized views that are currently being refreshed. This information is visible only on the materialized view site.
V$REPLPROP
contains information about the parallel propagation currently in progress at the replication site.
V$REPLQUEUE
contains statistics about the deferred transactions queue.
In addition, the DEFSCHEDULE
data dictionary view is enhanced for performance monitoring. The following columns are added to the DEFSCHEDULE
data dictionary view:
You can track dependencies between transactions at the row level instead of at the data block level. This feature enables parallel propagation to track dependencies and order changes more efficiently when applying the deferred transaction queue. This increased efficiency improves performance and provides greater scalability in replication environments.
CHAR
Column Length Semantics and Unicode
Replication supports CHAR
column length semantics and Unicode in both multimaster environments and materialized view environments.
Oracle has improved the Replication Management tool in Oracle9i with the following features:
In addition, the Replication Management tool is integrated with the Oracle Enterprise Manager Console in Oracle9i.
See Also:
Chapter 7, "Replication Management Tool Introduction" and the Replication Management tool online help |
The Oracle8i (release 8.1) replication features and enhancements described in this section comprise the overall effort to optimize replication performance and make materialized view environment distribution and security more effective. All of the features described in the following sections also apply to Oracle9i.
Release 8.1.7 and higher reduces the number of operations that require you to quiesce a master group in a single master replication environment. The following sections describe operations that no longer require quiesce in single master environments. In these sections, the replication management API procedure that corresponds to each operation is listed.
The following table lists the operations that no longer require quiesce in all single master replication environments. This table also lists the procedure in the DBMS_REPCAT
package that corresponds to each operation. In addition, these operations no longer require quiesce when you are using the Replication Management tool in DBA Studio (in release 8.1.7) or the Oracle Enterprise Manager Console (in Oracle9i).
In a single master environment, if none of the updatable materialized views use minimum communication in the detection of conflicts, then quiesce is no longer required for the administration operations to the master group listed in the following table. This table also lists the procedure in the DBMS_REPCAT
package that corresponds to each operation. In addition, these operations no longer require quiesce when you are using the Replication Management tool in DBA Studio (in release 8.1.7) or the Oracle Enterprise Manager Console (in Oracle9i).
Note: If at least one updatable materialized view is using minimum communication, then quiesce is not required if you perform the actions described in "Reduced Quiesce and Materialized Views in a Single Master Site Environment" |
See Also:
Oracle9i Replication Management API Reference for detailed information about using the procedures described previously in this section |
Significant performance gains are realized by the internalization of PL/SQL replication packages and by optimizations to materialized view refresh.
Continuing the trend started with Oracle8, more replication code has been moved into the database engine in Oracle8i. The PL/SQL generated packages used to apply replicated transactions at a remote site have been internalized. This allows replicated transactions to be more efficiently applied at remote sites, and, because packages are not generated, a site can be more quickly instantiated. Internal packages are also more secure because they are tamper proof.
Materialized view refresh has been optimized to support large refresh groups. There is improved support for subquery materialized views, and for null refresh (no changes to the master tables since the last refresh). A single refresh group can now contain 400 materialized views, and the number of roundtrips required to refresh materialized views in a refresh group has been reduced.
Oracle has improved replication support for the growing market of front office applications, in particular mass deployment.
Materialized view deployment templates can be instantiated online or offline. Online instantiation allows a materialized view site to instantiate the template while connected to the target master site. The advantage to online instantiation is that the data will be current at instantiation time. However, this is at the cost of requiring a live connection, possibly of long duration.
Offline instantiation allows the DBA to package the deployment templates and required data onto some type of storage media (tape, CD-ROM, and so on) for distribution to a materialized view site. Instead of connecting to the master site, instantiation can be done by pulling the template and data from the storage media. Users can fast refresh immediately after completing an offline instantiation; a full refresh is not required. Offline instantiation is an ideal solution for mass deployment situations where many disconnected laptops are instantiating the target template.
Deployment templates facilitate the mass deployment of information to support such applications as field service and sales force automation. These templates represent a grouping together of materialized views and other database objects to be instantiated at a node. They allow a DBA to centrally package a materialized view environment for easy, custom, and secure distribution to one or multiple sites. The goal is to create the environment once, and then deploy the template as often as necessary.
Template parameters allow data subsetting at a remote site without redefining the template, and a template may be defined as public or private. Public templates may be instantiated at any site, whereas private ones can only be instantiated at pre-defined, authorized sites. A Deployment Template Wizard guides the DBA through the selection of schema objects to add to the template, the selection of parameters, and defining authorizations. Deployment templates can be used to create materialized view environments at the following types of materialized view sites: Oracle Enterprise Edition, Oracle Standard Edition, and Oracle Personal Edition.
Updatable materialized views can now be subsetted by rows and columns. Previous release allow row subsetting only. Column subsetting allows the deployment of the minimum amount of data needed by a remote site, thus reducing connection time. It also protects materialized view sites from changes to their associated masters. A column can be added to a master site without impacting the materialized view site, or a column can be deleted and not impact the materialized view site, if the materialized view site does not currently reference that column.
While the scripts used to instantiate a materialized view site are generated at the master site and can control access to data, it is still necessary to connect to a receiver and proxy materialized view administrator to propagate replicated transactions and to refresh materialized views. Oracle8i enhancements to the replication security model eliminate certain security deficiencies regarding the granting of privileges to untrusted sites.
A number of improvements have been made to the Oracle Replication Management tool. A major enhancement is that it has been rewritten to conform to the new Java interface of Oracle Enterprise Manager. The Replication Management tool can now be run from anywhere in the network, and it is not constrained to Windows platforms. The Replication Management tool can also be run using a standard web browser. In addition, Oracle Enterprise Manager includes a replication class of events which, for example, can be used to monitor errors or delinquent materialized view refreshes.
The Replication Management tool has the following new wizards in Oracle8i:
Chapter 7, "Replication Management Tool Introduction" and the Replication Management tool online help
See Also:
The Oracle8 (release 8.0) replication features and enhancements described below comprise the overall effort to optimize multimaster replication performance and make certain types of materialized view subsetting fast refreshable. LOB support was added for Oracle8. Manageability and security were also enhanced for Oracle8. All of the features described in the following sections also apply to Oracle8i and Oracle9i.
Oracle8 provides significant performance improvements based on the following new features.
Oracle8 dramatically improves throughput performance by parallelizing the propagation of a replication transaction stream while maintaining consistency and transaction dependencies.
Oracle8 internalized replication triggers that were external in past releases are now internalized. Internal triggers:
Oracle8 reduces the amount of replicated data propagated over the network. Propagation can be reduced to only the following:
You accomplish this by:
min_communication
parameter in various procedures in the DBMS_REPCAT
package and the DBMS_OFFLINE_SNAPSHOT
package
SEND_OLD_VALUES
and COMPARE_OLD_VALUES
procedures in the DBMS_REPCAT
package
This feature is especially important for performance when replicating LOBs.
Materialized views defined with certain types of subqueries can now be fast refreshed. This enables subsets of data to be easily defined and maintained. This feature is important for mass deployment applications, such as sales force automation and branch automation.
Oracle8 supports the replication of the following types of large objects:
BLOB
s)
CLOB
s)
NCLOB
s)
The Replication Management tool online help for information on replicating object definitions to master sites and "Datatype Considerations"
See Also:
Oracle8 facilitates database management with the following features.
Replication master groups can now be individually quiesced without impacting other replication groups. Master groups can continue to process updates while other master groups are quiesced.
Primary key materialized views allow you to reorganize master tables while preserving fast refresh capability. Oracle8 adds primary key materialized views as the default and continues to support ROWID
materialized views.
See Also:
"Available Materialized Views". Also, see Oracle9i Database Migration for information about using |
Oracle8 automatically registers information about a materialized view at its associated master site. This facilitates monitoring and distributed administration.
Oracle8 provides utilities to enable you to reorganize master tables while preserving the consistency of materialized view logs.
See Also:
Oracle9i Replication Management API Reference for information about reorganizing master tables |
Offline instantiation of schemas and database using export/import is now more automatic.
See Also:
Oracle9i Replication Management API Reference for more information about adding new master sites using export/import |
Updatable materialized views now support declarative referential and uniqueness constraints.
Oracle8 supports the replication of partitioned tables and indexes. You can use this feature if you want the replicated table to have the same partitions as the table at the master definition site.
The Oracle8 system-based security model:
repadmin
user and repsys
user
The Replication Management tool now includes several wizards to help you configure your system quickly.
The Replication Management tool includes support for most new features of Oracle8 replication, including:
Chapter 7, "Replication Management Tool Introduction" and the Replication Management tool online help
See Also:
|
![]() Copyright © 1996-2001, Oracle Corporation. All Rights Reserved. |
|