Re: Rollback segment size

Do you have an optimal size set ?

If so, then what statistics are you getting about 'extends', 'shrinks' and 'wraps'.

If you run one very long transaction per week, then then over a period of a few weeks every rollback will get to a high water mark that matches that transaction, but this does not mean that the rollback segments should all be that large.

Try dropping and rebuilding at (say) 256K, with and optimal of 5Mb, work from there, aiming to pick an extent size where you have about 20 extents in steady state, where an occasional 'large extend' is allowed but regular small fluctuations do not occur.

I agree with SB - unlimited is a bad idea.

--

Jonathan Lewis
Yet another Oracle-related web site: www.jlcomp.demon.co.uk

Frank Calfo wrote in message <01be9ca3$a0db9520$e4010180_at_frank>...
>Our database was created with 4 rollback segments with initial and next
>extent size of 128K.
>I've noticed that highwater mark on them is approaching 30 MB and one just
>hit max extents limit.
>
>In our case, seems like 128K for next extent is rather small.
>
>Could I make it as large as 1MB or is that generally too large for a
>rollback segment?
>
>Also, is settting unlimited extents on rollback a good or bad idea?
>
>Thanks.
>
Received on Thu May 13 1999 - 02:55:45 CDT