Re: Oracle CBO question

  • From: "K Gopalakrishnan" <kaygopal@xxxxxxxxx>
  • To: jkstill@xxxxxxxxx
  • Date: Thu, 7 Jun 2007 13:18:55 -0700


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

Author: Oracle Database 10g RAC Handbook, Oracle Press 2006

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