Re: 9iR2 Logical Standby

Pete's wrote:
> Vital info:
>
> Both servers are at AIX 5.2 ml 03, Oracle 9.2.0.4 EE. Database, PROD1
> on SERVER1, QA_TEST1 on SERVER2.
>
> Questions:
> Has anyone ever setup a logical standby for only a couple tables into
> another database? I read through documentation on Logical Standby's
> and how to set them up, is it required to have a complete copy of the
> primary db to set it up on just a couple tables? Or is it just a
> matter of setting up the all the SQL APPLY & LOG Transport services
> correctly for it to work?
>
> TIA
> Pete's

Logical standby is based on the newer Oracle streams technology.

To create the logical standby, yes you do need a complete copy of the primary database, but once initialized, you can use the DBMS_LOGSTDBY package which "provide[s] a way to skip applying archived redo logs to selected tables or entire schemas in the standby database...". This is handy if, say, you only have a few schemas in your primary and just want one of them to be kept up to date in the standby, while at the same time allowing other objects to be created (or dropped) only in the standby. Another benefit is that all the information is contained in the archive redo logs and there is no impact on the primary when you apply updates to the standby (other than copying the archive redo logs).

On the other hand if you have hundreds of tables or dozens of schemas, and really do just want a few tables to be kept up to date, then it is probably overkill - try Advanced Replication (snapshots) instead, as another poster suggested.

Warning: a logical standby used for this purpose should not be considered an integral part of a disaster recovery plan (that is, don't think of trying to switch over to it if your primary fails).

-Mark Bole Received on Sat Nov 13 2004 - 14:17:21 CST