Re: Rollback Segment Setup Questions

Public rollback segments only work in parallel server, otherwise they act as private rollback segments.

On Thu, 24 Feb 2000 13:35:47 GMT, steyaert_at_my-deja.com wrote:

>I have to say that we do our rollback segments very differently. We
>also use 4 rollback segments, but have them defined as public, no
>private segments, and seem to be doing fine. We deal with a lot of
>data, in most cases, so we have fairly large database, tables and
>rollbacks. Our database is just shy of 1GB. (1000MB, actually) with
>the ROLLBACK datafile of 250MB (although we don't come near to filling
>it up. We define four public rollback segments (which in 8.1.5 are
>actually automatically created) of 1MB each, with next 1MB and
>pctincrease 0. These can grow to their heart's content, and with
>Oracle 8, vs. Oracle 6 when we first created our own rollback segments,
>will also shrink when the DB is bored.
>
>My original experience with the segments was due to Oracle 6. We would
>need to rebuild databases almost monthly because the database would
>fill up the datafile. The SYSTEM rollback segment would grow to huge
>levels, and the only way to shrink it was to export the database,
>delete the database, recreate the database, and re-import the
>database. Needless to say, an all-day job. By creating user rollback
>segments, we could clean up the occational large segment in minutes vs.
>hours. We also found greater throughput in the database.
>
>I am hoping we can get someone here with the actual math of optimizing
>rollback segments. For us, it was just trial and error.
>
>Terry Steyaert
>steyaert_at_my-deja.com
>
>
>Sent via Deja.com http://www.deja.com/
>Before you buy.

Christopher Spence
Senior MIS Engineer
A+ CNA Raptor Received on Thu Feb 24 2000 - 21:30:33 CST