Re: OPTIMAL on Roll Back Segments

paddy_nyr wrote:

> I'm using Oracle 8.1.7.4 on Solaris 8 and I'm getting a number of "snapshot
> too old" errors when I run my production process.
>
> I read that you should increase the number of rollbacks segments and so I
> did from 100 to 200, but still get the "snapshot too old"
>
> My initital storage is 5m, minextens 4, maxextents249, next 5m, optimal 20m.
>
> I read somewhere that not specifying an OPTIMAL size when creating your
> rollback segments helps because, if set, Oracle will dynamically shrink
> rollback segments which have grown larger than the specified size by
> deallocating extents. However, it may deallocate extents which still contain
> committed pre-images required for read-consistency. Not setting the OPTIMAL
> value eliminates this cause of "snapshot too old".
>
>
> Is this true?
>
>
> Thanks

Get rid of OPTIMAL and rather than adding more rollback segments ... make them larger.

That said is your code doing incremental commits? (commits inside of a loop). If so no change in rollback segments will save you from your code.

Go to http://asktom.oracle.com for a lot of very good advice on ORA-01555.

Daniel Morgan Received on Wed Jul 14 2004 - 20:31:33 CDT