Re: backup UNDO Tablespace (dba_undo_extents)
- From: Michael Fontana <michael.fontana@xxxxxxxxxxx>
- To: ian@xxxxxxxxxxxxxxxxx
- Date: Tue, 15 Dec 2009 11:15:53 -0600 (CST)
Oracle uses an algorithm to age out used blocks in the undo. Even though they
are not in use at any given point in time,
they must be cleaned out by an Oracle process and I know of nothing that can be
done directly to resize or release them.
Ian is right that they are REQUIRED for database recovery and should be backed
up regularly. Using compression
in your backup script if you're using RMAN should result in significant savings
IF the undo is marked as unused
based upon the algoritm. I've seen 80-90% compression rates for undo
datafiles. Your mileage may vary...
Michael Fontana
Sr. Technical Consultant
Enkitec M: 214.912.3709
enkitec
oracle_certified_partner
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