"snapshot too old" and undo

From: Roger Xu <roger_xu_at_dp7uptx.com>
Date: Thu, 29 Sep 2005 16:32:37 -0500
Message-ID: <A6801E8A03316A4DA597866F77A013F705183893@irv2kexch01.tx.bg.corp>

Hi List,

Background: Oracle 9.2.0 w/ Auto Undo Management

We have a huge table and it takes more than 24 hours to collect its statistics.

But the undo_retention is set to 864000 i.e. 24 hours. As a result we see the following a lot.

"ORA-01555: snapshot too old: rollback segment number 11 with name "_SYSSMU11$" too small"

Since we have lots of space in the undo tablespace, I am thinking of increasing undo_retention to 36 hours

via "ALTER SYSTEM SET UNDO_RETENTION = 129600;"

Is this my only choice?

What are the drawbacks to have a large undo_retention value assuming we never run out undo tablespace?

Thanks,

Roger Xu

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Received on Thu Sep 29 2005 - 16:35:09 CDT

"snapshot too old" and undo_retention