Re: Rollback segments not shrinking back to OPTIMAL size!

Hi Brian,

the RB shrinks only when it wraps. You have to use it a little bit and it will shrink.

HTH, Toni
In article <320F53F7.D24_at_cincom.com>, "Brian M. Biggs" <bbiggs_at_cincom.com> wrote:

> All,
>
>
>
> We have observed that with some of our application's long-running batch
> jobs, the rollback segments do not always shrink back to their OPTIMAL
> size. The way I understand rollback segments is that you are not
> guaranteed that a particular transaction will use a particular rollback
> segment. So, a transaction may cause a rollback segment to grow rather
> large, then commit, and the next transaction may not use the same
> rollback segment. Especially if the batch job is the only thing running
> in the database.
>
>
>
> We are using Oracle 7.1.6.2 on HP-UX 10.01. We have one rollback
> segment tablespace with 4 rollback segments, INITIAL and NEXT extents
> 5MB and OPTIMAL 20MB. When the batch job runs, one rollback segment
> grows very large (~50MB) before the job does the first commit. Then it
> resumes processing, and appears to use another rollback segment, which
> grows to ~170MB, and commits again. Eventually one of the rollback
> segments gives an ORA-01650 error because it runs out of room in the RBS
> tablespace. However, the other rollback segments are still at their
> expanded sizes of 50MB and 170MB.
>
>
>
> QUESTIONS
>
> ---------
>
> 1) Why didn't the rollback segments shrink back to their optimal size of
> 20MB?
>
> 2) What events trigger a rollback segment to rollback? Is it
> time-based?
>
>
>
> Thanks,
>
> Brian
>
>
>
> --
>
> Brian M. Biggs mailto:bbiggs_at_cincom.com
>
> Cincom Systems, Inc. voice: (513) 677-7661
>
> http://www.cincom.com/
 

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