Re: Which RBS is my Update using ?

Tanel Poder wrote:

> Hello!
>
> > There is no purpose served in asking the question. A properly configured
> > database has indistinguishable rollback segments. If you have need to
> > ask the question ... you have need to resize them.
>
> Not necessarily, for example, if I have a large OLTP system with lots of
> users, transactions, large DML and long-running selects. Then one might
> want to start using set transaction use rollback segment for directing
> large DMLs to separate, big RBSses, and if ORA-1555 still keep
> occurring, then as a first step, to see if the big transactions' undo
> went to right segment.
>
> The reason for not having all big rbs'es is simple - disk space.
> The reason for not having all medium sized rbs'es is also justified in
> some environments - rollback segment header contention
>
> Tanel Poder
> a DBA.

One might want to do what you suggest. But then again one might also wish to listen to Tom Kyte, Howard Rogers, and numerous other experts here at c.d.o. who will gladly tell you this is a bad practice and to not do it.

I'll repeat myself again ... if you need to ask the question you have your rollback segments improperly sized: They should all be identical and sized to handle the largest transaction on the system.

Check the google.com archives for the numerous postings by Tom and others on this subject.

Daniel Morgan Received on Tue Sep 17 2002 - 10:52:10 CDT