Re: ORA 1562 Rollback segment problem

Parris Geiser (parris_at_walleye.esp.bellcore.com) wrote:
: Hi,
: I have defined the table space for Rollback segments to a size
: of 4M. Our Product Test folks running a particularly large transaction,
: got ORA 1562. The transaction sometimes works and sometimes doesn't.
: In looking at the four segment sizes:
: RB1 532K
: RB2 665K
: RB3 2.5M
: RB4 400K
: Can anyone have a clue as to why the transaction sometimes fails?
: 4M seems like it should be enough space. Given that I'm in the
: situation, what is the best way now to get out?
 

: HP-UX with Oracle 7.0.16.4
 

: Thanks.

 Oracle places transactions in one and only one rollback segment. If your transaction needs 2.4 M of rollback entries, and it is lucky enough to be placed in RB3, it will succeed. If it goes into any of the others, it will fail. Oracle uses rollback segments in a cyclic manner. You can override this with the 'alter session set rollback segment RB3' sql*plus, or embedded command.

To see this, start your transaction while monitoring the rollbacks with Sqldba. Try to do this when nothing else is running, and look for the rollback with 1 Active Xaction. Thats where your transaction is running ...

-- 
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Jon Pope email:	jpope_at_mojo.europe.dg.com
European Database Competence Centre Manager
Data General UK Ltd.