Re: RBS problem

Use of Optimal is not advised if you value performance.

Rollback segments may *be able* to shrink and grow, but properly sized rollback segments will do neither under normal operating conditions, and that's exactly how things should be.

However, you obviously can't totally avoid unexpected growth in the event that you get a blocking transaction. The solution to which is NOT to let the rollback segment decide for itself when to shrink back, but to arrange for a manual shrink to take place at the dead of night -'alter rollback segment X shrink to 50M' will achieve the same degree of shrinkage as your suggestion, but will do it under your control, and at a time of your choosing.

None of which actually solves the original problem of growth of the rollback segment *tablespace* -which I imagine has happened because the segments have grown over time, and thus caused the tablespace datafiles themselves to auto-enlarge. The only way to get the tablespace itself back down in size now would be an 'alter datafile resize 100M' or some other appropriate size. Yet another good reason for never allowing datafiles to be created autoextensible.

Regards
HJR "Tom Best" <tom.best_at_bentley.com> wrote in message news:8kn4fi$dtr$1_at_news.bentley.com...
> Yes, optimal will solve this. Use
>
> ALTER ROLLBACK SEGMENT <rbsname> OPTIMAL 50M
>
> to tell Oracle to, during normal operations, attempt to deallocate unused
> extents until it gets back to 50 meg.
>
> Use:
>
> ALTER ROLLBACK SEGEMENT <rbsname> SHRINK
>
> to attempt to shrink it down right now, to the optimal size.
>
> HTH.
> Tom Best
>
> <dlane_at_cix.compulink.co.uk> wrote in message
> news:8klhbc$1cf$1_at_plutonium.compulink.co.uk...
> > Did you set 'optimal' in the storage clause when you created the
 rollback
> > segments?
> >
> >
> > Dave Lane (dlane_at_pt.lu)
> >
> >
> > In article <8kjush$5lj$1_at_nnrp2.deja.com>, tigsar_at_my-deja.com () wrote:
> >
> > > Can anybody say me
> > >
> > > Why the rollback tablespace is enlarging;
> > > Default size of rbs (when installing) was 50Mb, now it 580Mb
> > >
> > > Thanks
> > >
> > >
> > > Sent via Deja.com http://www.deja.com/
> > > Before you buy.
>
>
Received on Sun Jul 16 2000 - 00:00:00 CDT