Re: Rollback Segment Setup Questions

The upper limit of 50 was in an old, old release (6.0.something). It was really only due to the fact that we couldn't put more than that in the rollback_segments parameter and have the file parsed successfully. I've known people who created more than 2,000 (as a test), so I'd be inclined to use the 4 to 1 rule and check v$waitstat to see if there are waits for undo header blocks.

HTH. Pete

Niall wrote:

> the general rule is the rule of 4. 1 rollback segment for every 4 active
> users of the database. There is an upper limit of 50 rollback segments
> recommended by Oracle. Sizing is more difficlt because it depends on usage
> patterns, but I would recommend smallish equally sized rollback segments for
> an OLTP system with perhaps a couple of large ones offline that can be
> brought online for any batch processing that is required.
>
> "Michael Wilkerson" <mwilker_at_texas.net> wrote in message
> news:38B4C1E4.AE721295_at_texas.net...
> > As a general rule, how many rollback segments should I create for my
> > database and how big should I make each one? Should they all be the
> > same size or does it make sense to vary the sizes? Finally, what should
> > be the mix between system and public rollback segments?
> >
> > I guess I'm just looking for some general pointers here. Not sure how
> > much detail is required to really go into an indepth answer for the
> > above. Any insight is greatly appreciated.
> >
> > Michael
> >

Received on Fri Feb 25 2000 - 11:16:15 CST