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Re: Oracle CBO question

From: K Gopalakrishnan <kaygopal_at_gmail.com>
Date: Thu, 7 Jun 2007 13:18:55 -0700
Message-ID: <3b0f44a10706071318j56e3fe03m65500980549de0e2@mail.gmail.com>


Jared,

N factorial permutations for N tables are theoretical limit. However in practice the number of combinations are optimized (read: limited) to a much smaller number than the thousands. If you start examining all the thousands of combinations the parse time itself will run for minutes and to avoid that there are limits defined for everywhere. There is an 'optimizer_search_limit' and also '_new_initial_join_orders' limits the number of permutations .

-- 
Best Regards,
K Gopalakrishnan
Co-Author: Oracle Wait Interface, Oracle Press 2004
http://www.amazon.com/exec/obidos/tg/detail/-/007222729X/

Author: Oracle Database 10g RAC Handbook, Oracle Press 2006
http://www.amazon.com/gp/product/007146509X/
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Received on Thu Jun 07 2007 - 15:18:55 CDT

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