OPTIMAL on Roll Back Segments

I'm using Oracle 8.1.7.4 on Solaris 8 and I'm getting a number of "snapshot too old" errors when I run my production process.

I read that you should increase the number of rollbacks segments and so I did from 100 to 200, but still get the "snapshot too old"

My initital storage is 5m, minextens 4, maxextents249, next 5m, optimal 20m.

I read somewhere that not specifying an OPTIMAL size when creating your rollback segments helps because, if set, Oracle will dynamically shrink rollback segments which have grown larger than the specified size by deallocating extents. However, it may deallocate extents which still contain committed pre-images required for read-consistency. Not setting the OPTIMAL value eliminates this cause of "snapshot too old".

Is this true?

Thanks Received on Wed Jul 14 2004 - 12:14:11 CDT