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Other people have mentioned that running ANALYZE estimate will indeed
overwrite the COMPUTE stats. I would like to add that the frequency for
doing analyze really depends on the rate of changes to the data. If the data
is fairly static your monthly may be enough to keep up. If on the other hand
you are doing a lot of OLTP with the inserts and updates really flying you
may want to a look at daily estimates during off hours. Then you could tune
the few problem-child queries using fixed plans and hints to make up for CBO
quirks and use 25% estimates. Someone suggested 49% estimates, but that's so
close to the 50% of a COMPUTE analyze that I don't know if it's worth the
difference. Perhaps if someone has determined that a 50% estimate is still
faster than a COMPUTE that would be interesting.
Regards,
Chris Gait
> We have a database set to CHOOSE. Although we would like to
> run compute statistics weekly on a particular schema's tables,
> it takes too long. If we were to do compute statistics once
> per month and estimate statistics weekly, would that be efficient?
> When estimate statistics is done is it overriding all of the
> statistics from compute statistics?
Received on Mon Jul 10 2000 - 14:11:08 CDT