Re: [Q] what differtent between logical standby database and physical standby DB?

From: Tanel Põder <tanel.poder.003_at_mail.ee>
Date: Thu, 8 Apr 2004 19:40:38 +0300
Message-ID: <019d01c41d88$3aedd780$0ea623d5@porgand>

> Um, in the physical standby case, aren't the archivelogs simply =
> transferred to the standby server in their entirety? To the best of my =
> knowledge, physical standby doesn't do logmining, right?

It doesn't do logmining, but however, in both cases the changes have to be constructed from change vectors (and supplemental information) in redo records, the difference is that in logical apply scenario sql statements are constructed and passed to higher layer for sql processing, but in physical apply just datablocks are read and changes are applied to them directly (using kernel cache layer?).

The point I was trying to make was, that in both cases you have to parse the redo records to get the changes, that way you'd detect corruptions equally in both cases as well... yes SQL apply ignores some of the redo vectors in logs but on the other hand, it requires additional, supplemental records for its operations...

Tanel.

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Received on Thu Apr 08 2004 - 11:40:23 CDT