Re: DBMS_STATS

  • From: Mogens Nørgaard <mln@xxxxxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Wed, 16 Jun 2004 09:55:54 +0200

Can't remember if you got any responses on this - if you did, then I apologize for any repetitions...

There's no correct answer to this question - if there was, it would be part of the DBMS_STATS thing now, I bet :-)

I would suggest the following (subject to debate, please):

1. Collect stats (sample 1 percent) on all your objects OR
2. Import stats from your test system (or another similar system)
3. If there are performance problems somewhere, fix them with either SQL statement tuning or Breitlings methods, or whatever
4. If a table grows a LOT in size, re-analyze.
5. Otherwise, don't touch anything until somebody complains. What Peter Gram from Miracle has called Compulsive Analyze DisOrder (CADO) is perhaps fun, but mostly not needed.


Why the 1 percent sample? Because that's what the Oracle benchmark guys do, so I figured it might be good enough. From a purely statistical point of view it ought to be, too.

Special problems exist, but this is my first suggestion.

Mogens

April Wells wrote:

Carel-Jan

It is a really good paper, one that I will now read over pretty
extensively... but I'm not sure it answers her questions on DBMS_STATS and
how best to collect statistics effectively.

I do want to see any good doc on it to.  We are using DBMS_STATS in
production, in all of our instances, but I'm not comfortable that we are
implementing as well as we could, either.

ajw

April Wells
Oracle DBA/Oracle Apps DBA
Corporate Systems
Amarillo Texas
@>-->-->--
"Few people really enjoy the simple pleasure of flying a kite"
Adam Wells age 11
"Imagination is the highest kite one can fly."
Lauren Bacall






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