Irrelevant thoughts of an oracle DBA

20 October 2009

Multiple standby databases and supplemental logging

Filed under: dataguard,infrastructure — Freek D'Hooge @ 18:10

A quick warning:

When you setup a logical standby database, you need to activate supplemental logging on the primary database.
This is done automatically when you build the data dictionary (by running the procedure).
Activating supplemental logging is however (I know now) a control file change and is thus not replicated to the other physical standby databases.
As a result, the logical standby will become (logical) corrupt when you perform a role switch between your primary and another physical standby database.

I learned this the hard way  :(
Luckily it was during a proof of concept and not in a real production environment … .

Of course, AFTERWARDS, I found the following maa document which points out that you have to enable supplemental logging yourself on the other physical standby databases.
It still makes a good read though

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