From: =?iso-8859-1?q?C=E9dric_Villemain?= <cedric@2ndquadrant.com>
Reply-To: cedric@2ndquadrant.com
Organization: 2ndQuadrant
To: pgsql-performance@postgresql.org
Subject: Re: non index use on LIKE on a non pattern string
Date: Fri, 8 Jun 2012 13:51:50 +0200
User-Agent: KMail/1.13.7 (Linux/3.2.0-2-amd64; KDE/4.7.4; x86_64; ; )
Cc: Guillaume Cottenceau <gc@mnc.ch>
References: <m3mx4eys6o.fsf@mnc.ch>
In-Reply-To: <m3mx4eys6o.fsf@mnc.ch>
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> I have noticed that with a SELECT query containing the following
> constraint:
>=20
>     column LIKE ?
>=20
> 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 "=3D" in your case, since 8.4

Also you probably want to have a look at
 http://www.postgresql.org/docs/9.1/static/indexes-opclass.html=20
about your index definition (add the "text_pattern_ops" when required)

=2D-=20
C=E9dric Villemain +33 (0)6 20 30 22 52
http://2ndQuadrant.fr/
PostgreSQL: Support 24x7 - D=E9veloppement, Expertise et Formation

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