From: Cédric Villemain <cedric@2ndquadrant.com>
To: pgsql-performance@postgresql.org
Cc: Guillaume Cottenceau <gc@mnc.ch>
Subject: Re: non index use on LIKE on a non pattern string
Date: Fri, 8 Jun 2012 13:51:50 +0200
Message-ID: <201206081351.54589.cedric@2ndquadrant.com> (raw)
In-Reply-To: <m3mx4eys6o.fsf@mnc.ch>
References: <m3mx4eys6o.fsf@mnc.ch>
> 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
Also you probably want to have a look at
http://www.postgresql.org/docs/9.1/static/indexes-opclass.html
about your index definition (add the "text_pattern_ops" when required)
--
Cédric Villemain +33 (0)6 20 30 22 52
http://2ndQuadrant.fr/
PostgreSQL: Support 24x7 - Développement, Expertise et Formation
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To: pgsql-performance@postgresql.org
Cc: cedric@2ndquadrant.com, gc@mnc.ch
Subject: Re: non index use on LIKE on a non pattern string
In-Reply-To: <201206081351.54589.cedric@2ndquadrant.com>
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