Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Mailing Lists -> Oracle-L -> Max permutations

Max permutations

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Mon, 9 Feb 2004 15:51:55 -0000
Message-ID: <017201c3ef24$a5aa2c00$6702a8c0@Primary>

Has anyone done any recent testing on the effect of optimizer_max_permutations.

I recall seeing a note on metalink once said the CBO would change the way in which it permuted join orders if the parameter was set to any value other than 80,000. I'm also fairly sure that I ran up a test a few years ago that demonstrated this effect.

However, I've just run up a simple test on 8.1.7.4 and 9.2.0.4 where the only change was the number of join orders examined
before the optimizer stopped (a few hundred for omp = 2000, a couple of thousand for omp-80000) - the permutation sequences were was identical.

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

  The educated person is not the person   who can answer the questions, but the   person who can question the answers -- T. Schick Jr

Next public appearances:
 March 2004 Hotsos Symposium - The Burden of Proof  March 2004 Charlotte NC OUG - CBO Tutorial  April 2004 Iceland

One-day tutorials:
http://www.jlcomp.demon.co.uk/tutorial.html

Three-day seminar:
see http://www.jlcomp.demon.co.uk/seminar.html
____UK___February
____UK___June

The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html



Please see the official ORACLE-L FAQ: http://www.orafaq.com

To unsubscribe send email to: oracle-l-request_at_freelists.org put 'unsubscribe' in the subject line.
--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------
Received on Mon Feb 09 2004 - 09:51:55 CST

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US