RE: ORA-1555 error with AUM already enabled

> Is this just one of those freak cases where circumstances have psyched out the

> automatic feature, or is there something I can do to fix it, beyond whatever 
> the manager is doing?  Clearly the immediate problem is that my rollback 
> segments are too small, but since Oracle is managing them I hesitate to go make 
> them bigger myself.

Janine,

as pointed out by Mark it would be helpful to know the database version that you're using.

Regarding your doubts I recommend to read this:

http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/undo.htm#BJFFIACJ

Starting from Oracle 10 on the undo retention is indeed auto-tuned which means that the UNDO_RETENTION setting is merely an indicator (or even ignored, except for the RETENTION GUARANTEE case where it is the minimum guaranteed retention).

You can monitor the auto-tuned undo retention in V$UNDOSTAT.TUNED_UNDORETENTION.

Oracle uses different auto-tune approaches depending on the undo tablespace being fixed-size or auto-extensible - it is described in the link above.

But as you've pointed out - it doesn't change the fact that the undo retention (that Oracle "auto-tunes" if 10g or later) is too small for your case - which probably means your undo tablespace is simply too small or you're still on 9i in which case you need to increase the parameter since no auto-tuning is taking place.

Regards,
Randolf

Oracle related stuff blog:
http://oracle-randolf.blogspot.com/

Co-author of the "OakTable Expert Oracle Practices" book:
http://www.apress.com/book/view/1430226684
http://www.amazon.com/Expert-Oracle-Practices-Database-Administration/dp/1430226684