10.2.0.4 logic standby 问题

taoy_2008

10.2.0.4 逻辑DG是不是有一些限制，如所有的表要有主键或者唯一键，不支持CLOB,BLOB数据类型。产生的日志也比较多。

os ：aix 6.1

oracle：10.2.0.4.

Maclean Liu(刘相兵

Unsupported Datatypes in a Logical Standby Database

Logical standby databases do not support the following datatypes:


BFILE
Collections (including VARRAYS and nested tables)
Multimedia data types (including Spatial, Image, and Oracle Text)
ROWID, UROWID
User-defined types
LOBs stored as SecureFiles
XMLType stored as Object Relational
Binary XML


Unsupported Table Storage Types

Logical standby databases do not support the following table storage types:

Tables stored with segment compression enabled
Tables containing LOB columns stored as SecureFiles
Tables with virtual columns

Unsupported PL/SQL Supplied Packages

Oracle PL/SQL supplied packages that modify system metadata typically are not supported by SQL Apply, and therefore their effects are not visible on the logical standby database. Examples of such packages are DBMS_JAVA, DBMS_REGISTRY, DBMS_ALERT, DBMS_SPACE_ADMIN, DBMS_REFRESH, DBMS_REDEFINITION, and DBMS_AQ.

Specific support for DBMS_JOB has been provided. Job execution is suspended on a logical standby database and jobs cannot be scheduled directly on the standby database. However, jobs submitted on the primary database are replicated in the standby database. In the event of a switchover or failover, jobs scheduled on the original primary database will automatically begin running on the new primary database.

Specific support for DBMS_SCHEDULER has been provided to allow jobs to be run on a standby database. A new attribute of a scheduler job has been created in 11g called database_role whose contents match the database_role attribute of V$DATABASE. When a scheduler job is created, it defaults to the local role (that is, a job created on the standby defaults to a database_role of LOGICAL STANDBY). The job scheduler executes only jobs specific to the current role. On switchover or failover, the scheduler automatically switches to running jobs specific to the new role.

Scheduler jobs are not replicated to the standby. However, existing jobs can be activated under the new role by using the DBMS_SCHEDULER.Set_Attribute procedure. Alternatively, jobs that should run in both roles can be cloned and the copy made specific to the other role. The DBA_SCHEDULER_JOB_ROLES view shows which jobs are specific to which role.

Scheduler jobs obey the database guard when they run on a logical standby database. Thus, in order to run jobs that need to modify unmaintained tables, the database guard should be set to STANDBY. (It is not possible to use the ALTER SESSION DISABLE GUARD statement inside a PL/SQL block and have it take effect.)


Unsupported Tables

It is important to identify unsupported database objects on the primary database before you create a logical standby database because changes made to unsupported data types and tables on the primary database will be automatically skipped by SQL Apply on the logical standby database. Moreover, no error message will be returned.

There are three types of objects on a database, from the perspective of logical standby support:

Objects that are explicitly maintained by SQL Apply
Objects that are implicitly maintained by SQL Apply
Objects that are not maintained by SQL Apply


Skipped SQL Statements on a Logical Standby Database

By default, the following SQL statements are automatically skipped by SQL Apply:


ALTER DATABASE
ALTER MATERIALIZED VIEW
ALTER MATERIALIZED VIEW LOG
ALTER SESSION
ALTER SYSTEM
CREATE CONTROL FILE
CREATE DATABASE
CREATE DATABASE LINK
CREATE PFILE FROM SPFILE
CREATE MATERIALIZED VIEW
CREATE MATERIALIZED VIEW LOG
CREATE SCHEMA AUTHORIZATION
CREATE SPFILE FROM PFILE
DROP DATABASE LINK
DROP MATERIALIZED VIEW
DROP MATERIALIZED VIEW LOG
EXPLAIN
LOCK TABLE
SET CONSTRAINTS
SET ROLE
SET TRANSACTION

Maclean Liu(刘相兵

由于logical standby需要加supplement log 才能正常使用， 视乎 表上的实际情况(是否有主键或unique index很重要) 决定日志的产生量，当表上没有这样的约束时 且 列非常多时 可能产生大量日志。 实际有 表上超过255列且无良好索引的情况，产生 多倍日志的情况。