RE: Rollback Segment Philosophy

From: Mercadante, Thomas F <thomas.mercadante_at_labor.state.ny.us>
Date: Tue, 20 Jul 2004 13:47:12 -0400
Message-ID: <DE8A21F8F1D0254EA4A9214D52AB2FEDAD5CF6@exchsen0a1ma>

Kevin,

My philosophy about Rollback Segments is to have enough and the correct size so that we never experience a "Snapshot too old".

Beyond that, it all comes down to implementation. I end up sizing the rollbacks so that 99% of the time, everything works fine. If a job blows up because of rollback problems, I ask the application folks to redesign it - change the commit strategy so that it doesn't happen again.

It's all a balance between reserving (wasting) too much space in Rollback Segments and getting the job done. Sometimes you have to add rollback segment space, and sometimes the applications folks need to alter the job being run.

Hope this helps.

Tom Mercadante
Oracle Certified Professional

-----Original Message-----

From: Kevin Lange [mailto:klange_at_ppoone.com] Sent: Tuesday, July 20, 2004 1:36 PM
To: 'oracle-l_at_freelists.org'
Subject: Rollback Segment Philosophy

Evening;
Is there 'accepted' philosophy on Rollback Segments and how many and how big they should be ?

We are running an 8.1.7.4 database on Solaris 5.9. The database is a hybrid Transactional with some long running processes.

We have always made it a point to have a limited number of rollback segments using a limited amount of space. But, the issue of no space no longer applies.

Since we are starting to get rollback issues due to running out of space on our rollback segments we have decided to reopen our analysis of our rollback design.

I was just wondering if any of you would mind sharing your philosophy on Rollbacks .

Thanks

Kevin

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Received on Tue Jul 20 2004 - 12:45:06 CDT