Oracle-L: Re: oracle logical standby

From: Paul Baumgartel <treegarden_at_yahoo.com>
Date: Fri, 01 Aug 2003 12:29:24 -0800
Message-ID: <F001.005C848F.20030801122924@fatcity.com>

We were going to use logical standby but quickly abandoned the idea after testing.

The APPLY process on the standby crashed regularly (every 10 minutes or so). Oracle claimed it was a fixed bug, but there was no port to Windows, so we'd have had either to wait for the next RDBMS release or request a patch...with implementation a month or so away, we didn't want to take the chance.
DDL in the apply stream is problematic, also causing apply slave crashes.
Performance of the apply slave is horrendous. Since Logical Standby uses LogMiner to construct SQL statements from redo information, and since redo information consists of block change vectors, a 10,000-row delete in the redo becomes...10,000 DELETE statements in the apply process. I found that the time for application of changes on the standby was about an order of magnitude greater than the time taken for the original changes on the master; and this was after applying a few (but not all) of Oracle's standby tuning suggestions.

Also, we are planning to use Oracle Label Security, but it is not compatible with Logical Standby.

There are a number of Documentation bugs (including bugs in Notes posted on MetaLink that are supposed to correct earlier Doco bugs!) in the sections regarding how to set up a logical standby; be sure you follow the 9.2.0.3.0 docs' instructions for that. Don't use the notes on MetaLink!

Now, for the good stuff.

Well, it worked sometimes....

Really, it's a brand-new feature, and performs as brand-new Oracle features typically do--it's buggy and it's slow.

Well,

"Loughmiller, Greg" <Greg.Loughmiller_at_cingular.com> wrote:
> folks -
> listening to a preso from a vendor where they will use logical
> standby to
> accomplish some of the 99.999999999999999 availability
> requirements... so
> I'm wondering, does anyone have some extensive experience with the
> logical
> standby to share? the good stuff, the bad stuff, pitfalls, gotcha's,
> and
> general things to run away from.. Then on the other hand-what things
> should
> someone try to leverage?
>
> thanks in advance!
>
>
> Greg Loughmiller
>
>
>

Paul Baumgartel
Transcentive, Inc.
www.transcentive.com

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Author: Paul Baumgartel
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Received on Fri Aug 01 2003 - 15:29:24 CDT