Rollback Segments

From: Buergi Joseph <Josef.Buergi_at_ASCOM.CH>
Date: Fri, 9 Feb 1996 14:39:00 +0100
Message-Id: <9602091521.AA13515@alice.jcc.com>

Hello

There is a problem concerning rollback segments which I don't understand.

I created the following rollback segment (one of a few)

CREATE ROLLBACK SEGMENT rbs_04

  STORAGE(INITIAL       16K
          NEXT          16K
          MINEXTENTS    5
          MAXEXTENTS    121
          OPTIMAL       130K)

TABLESPACE rbs_small;

Then I forced a delete over a large table (using set transaction use rollback segment rbs_04), and monitored the RBS-segments . The extents grew to 121, as supposed. On sqlplus the error "cannot allocate extent in rollback segment rbs_04" occured. The maximum of extents were exceeded. Ok, so far!

But - I thought that ORACLE frees the allocated extents in that RBS to the optimal size (130k), after the end of transaction (dynamic extent management).

So - I tried to delete a short number of records (10) to see, what happens. What I got were the following errors "error freeing extent in tollback segment" and "attempt to wrap into rollback segment .... extent which is being freed".

Now my question:

When does ORACLE free its rollback extents, or which process does it ?

Not even a shutdown has helped to reuse that rbs segment again.

Any help ?

Regards, Joseph Received on Fri Feb 09 1996 - 10:21:41 CST