Re: URGENT! HELP needed on rollback segs

You might create a tablespace just for rollback segments. It is a good idea not to keep the rollback segments in the sytem tablespace, and they might fragment the the tablespace, making it difficult to extend data dictionary tables located here. If it is fragmented you might suffer in performance as the data dictionary tables are updated.

If you are using oracle 7 look up the OPTIMAL clause in the dba book, This will allow a rollback segment to shrink back in size when a transaction is finished with it. We run three rollback segments of 20 meg each in a 100 meg tablespace. If a transaction needs more than 20 M of rollback space it will extend its rollback segment by 1 M bits until either it finishes or grows to 60 M and attempts to exceed the avaialable space in the tablespace (three 20M rollbacks = 60 M, leaving 40 M for growth.) Once the transaction is finished the tablespace is returned to the original 20, leaving the 40M for another transaction. Received on Fri Apr 15 1994 - 02:05:20 CEST