Re: optimizer_max_permutations

From: Connor McDonald <hamcdc_at_yahoo.co.uk>
Date: Tue, 26 Aug 2003 07:54:36 -0800
Message-ID: <F001.005CD490.20030826075436@fatcity.com>

One thing that the docs don't mention is that '80000' (the default in 8) is also a special boundary value. Anything less than 80,000 changes some of ways the optimizer does it work, ie, its not just a reduction in permutations.

Can't remember the specifics - join orders spring to mind but there is a metalink note about it.

Because of this, there's a school of thought that even on 8i, adopting the (9i default) value of 2000 will improve the "general" optimizer performance (ie the quality of the decisions it makes).

Cheers
Connor

• "Boivin, Patrice J" <BoivinP_at_mar.dfo-mpo.gc.ca> wrote: > Has anyone worked with this one?
  >
  >
  http://download-west.oracle.com/docs/cd/A87860_01/doc/server.817/a76961/ch11
  > 23.htm#81357
  >
  <http://download-west.oracle.com/docs/cd/A87860_01/doc/server.817/a76961/ch1
  > 123.htm#81357>
  >
  > Patrice.
  >
  

  ---

Connor McDonald
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"GIVE a man a fish and he will eat for a day. But TEACH him how to fish, and...he will sit in a boat and drink beer all day"

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Received on Tue Aug 26 2003 - 10:54:36 CDT