Jared, I think your conclusions must have assumptions:
1) The SQL was written "correctly".
2) The data structures wrer designed and layed out properly.
Here, we can AssUMe neither. :)
Food for thought...
Rich
Rich Jesse System/Database Administrator
[EMAIL PROTECTED] Quad/Tech Inc, Sussex, WI USA
-----Original Message-----
Sent: Tuesday, December 30, 2003 4:29 PM
To: Multiple recipients of list ORACLE-L
Mogens,
Quite a controversy you started here.
As always. ;)
I must admit this is the first time I've heard this come up.
As Jonathan stated, it does seem somewhat like rebuilding indexes.
But then again, if re-collecting statistics causes your database performance
to suddenly become very bad, it seems at first cut there are only two
conclusions
you can come to.
1) CBO is broke if fresh statistics result in poor performance
2) statistics were collected at a time when temporary conditions
created different statistics than what would normally appear.
ie. at night when batch jobs are being run with lots of DML.
No. 2 seems the likely candidate, unless of course, it's both 1 and 2.
If just 2, then from a users perspective, it would seem most appropriate
to have statistics collected during the day, when people are banging
away on the OLTP stuff.
But then, might that play havoc with the batch jobs?
How about 2 sets of statistics. Import the OLTP stats in the morning for
the users, and the BATCH stats at night for the batch jobs.
I'm not sure if I should laugh at that, or not.
Jared
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