[Commits] Rev 2822: Fixed bug #52636. in file:///home/igor/maria/maria-5.3-mwl128-bug52636/

igor at askmonty.org igor at askmonty.org
Tue Sep 28 06:56:37 EEST 2010

At file:///home/igor/maria/maria-5.3-mwl128-bug52636/

revno: 2822
revision-id: igor at askmonty.org-20100928035521-6yej211phul6e01q
parent: igor at askmonty.org-20100923182545-fjwtj40q55lanx89
committer: Igor Babaev <igor at askmonty.org>
branch nick: maria-5.3-mwl128-bug52636
timestamp: Mon 2010-09-27 20:55:21 -0700
  Fixed bug #52636.
  Applied the fix for bug #47217 from the mysql-6.0 codebase.
  The patch adds not null predicates generated for the left parts
  of the equality predicates used for ref accesses. This is done
  for such predicates both in where conditions and on conditions.
  For the where conditions the not null predicates were generated
  but in 5.0/5.1 they actually never were used due to some lame
  merge from 4.1 to 5.0. The fix for bug #47217 made these 
  predicates to be used in the condition pushed to the tables.
  Yet only this patch generates not null predicates for equality
  predicated from on conditions of outer joins.
  This patch introduces a performance regression that can be
  observed on a test case from null_key.test. The regression
  will disappear after the fix for bug #57024 from mariadb-5.1
  is pulled into mariadb-5.3.
  The patch contains many changes in the outputs of the EXPLAIN 
  commands since generated not null predicates are considered as
  parts of the conditions pushed to join tables and may add
  'Using	where' in the some rows of EXPLAINs where there used
  to be no such comments.
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