Re: Rollback Segs

kal121_at_yahoo.com wrote:
>
> Hi,
> I am creating 10 rollback segs, initial extent 50K, next extent 50K.
> My question is, is it better to set maxexents UNLIMITED, and set the OPTIMAL
> to some value to provide shrinkage
> OR
> put a cap on the number maxextents to begin with, eg) maxextents = 250 and run
> the risk of running out of extents on a transaction.
>
> Thanks,
> KL

I have never liked the use of umlimited segments -- but you can use it. You should always set the optimal.
My minimum rules of thumb:

1. Create rollbacks with initial extent size = nextextent size
2. set minextents equal to 20
3. set the optimal slightly larger than 20 extents -- this way rollbacks will shrink back down to the optimal size if they expand.
4. I like to cap my extents at double or triple the min-extent #

example of storage:
create rollback .....
storage (initial 1M next 1M minextents 20 maxextents 60 optimal 22M)
tablespace RBS;

BTW, a 50K rollback segment sounds really small -- I have never seen any applications/transactions really below 250K segment size...

sincerely,
darryl dB Balaski
DBA
Pfizer Central Research Received on Thu Nov 12 1998 - 15:42:24 CST