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Re: performance impact of optimizer_search_limit

From: A. Bardeen <abardeen1_at_yahoo.com>
Date: Sat, 16 Jun 2001 13:45:25 -0700
Message-ID: <F001.0032C85E.20010616135052@fatcity.com>

Steve,

You might also want to test setting
optimizer_max_permutations < 80000.

By design, the CBO considers multiple starting tables and restricts permutations during OR expansion when optimizer_max_permutations < 80000. This can have a significant impact on queries that join a large number of tables or have a large number of OR expansions.

I believe apps 11i (not sure about 11.0), for example, recommends setting this to 79999.

HTH,


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Received on Sat Jun 16 2001 - 15:45:25 CDT

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