Re: Rollback Segment Setup Questions

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

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Before you buy. Received on Thu Feb 24 2000 - 07:35:47 CST