Undo Tablespace question
- From: "Paul Vincent" <Paul.Vincent@xxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 17 Sep 2004 09:16:15 +0100
Now that we've finally got some 9i databases, I'm quite keen to switch =
from Manual to Automatic Undo Management. It all looks pretty =
straightforward, but I do have a couple of questions that the "How To" =
guides don't really address...
1. If I don't have any requirement for long-term retention of Undo data =
after transactions commit, so that the default retention of 900 seconds =
is quite sufficient, then what multiplier should I use when calculating =
the size of my Undo Tablespace relative to the size of the old RBS =
tablespace? Say I currently have 500Mb RBS tablespace, then should a =
500Mb undo tablespace be adequate, or should I allow double (1Gb) or =
more?
2. What monitoring practices are advisable to check the adequacy of the =
undo tablespace provision? Can anyone point me at any webpages with =
articles about monitoring AUM activity, for instance?
3. Once I've switched from Manual to Auto, does the RBS tablespace then =
become completely superfluous? Can it be dropped? And what of the =
"rollback_segments" initialisation parameter? Do I remove this from the =
parameter file, or is it best left there "just in case"?
Before I go diving in, in cavalier manner, I always like to check for =
"gotchas"!
Regards,
Paul Vincent
DBA
University of Central England
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