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

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Received on Mon Feb 09 2004 - 09:51:55 CST