Re: Undo Management

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shirleyr_at_mailings.com wrote:
> Hi,
>
> I did most of my work on Oracle 8i using rollback segments. I just
> took a new job where they didn't have a DBA before and are using Oracle
> 9i and 10g. They have Undo tablespaces instead of rollback segments.
> Does undo tablespaces work like rollback segements? Can someone point
> me to some reading to explain how they should be set up and how they
> work. We have a long transaction that has been running at night and it
> gets 'snapback too old' error message. But I don;t know how the undo
> is working. Should I remove all the undofile to have just one undofile
> to use all the space for this transaction?
>

Make sure you set the undo_retention parameter high enough to let that transaction complete. And make sure the undo tablespace is big enough to retain the undo information for that long. You can estimate it based on the contents of v$undostat.

HTH
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