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Le vendredi 8 juin 2012 15:57:07, Tom Lane a écrit : > =?iso-8859-1?q?C=E9dric_Villemain?= <cedric@xxxxxxxxxxxxxxx> writes: > >> I have noticed that with a SELECT query containing the following > >> constraint: > >> > >> column LIKE ? > >> > >> and an index on that column, PostgreSQL will not use the index > >> even if the parameter doesn't contain special pattern characters > >> such as %. > > > > you should have a postgresql 8.3,isn't it ? > > > > like is equal to "=" in your case, since 8.4 > > No, the planner has understood about wildcard-free LIKE patterns > producing an "=" index condition at least since 7.3. I think what the > OP is complaining about is the problem that the pattern has to be > actually constant (ie, NOT a parameter) before it can be optimized into > an index condition. This should be better in 9.2 ...
Oops, maybe I shuffled with this * xxx_pattern_ops indexes can now be used for simple equality comparisons, not only for LIKE (Tom)
-- Cédric Villemain +33 (0)6 20 30 22 52 http://2ndQuadrant.fr/ PostgreSQL: Support 24x7 - Développement, Expertise et Formation |
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