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Re: Index usage btree+gist ?

From: Arnaud Lesauvage <thewild(at)freesurf(dot)fr>
To:
Cc: pgsql-novice(at)postgresql(dot)org
Subject: Re: Index usage btree+gist ?
Date: 2006-02-17 15:06:07
Message-ID: 43F5E65F.4050704@freesurf.fr (view raw or flat)
Thread:
Lists: pgsql-novice
Tom Lane a écrit :
> Arnaud Lesauvage <thewild(at)freesurf(dot)fr> writes:
>> I have a table with a lot of rows (~3.000.000 I believe), and two
>> indexes.
>> The first one is a BTree index on a column (lets call it
>> btreecolumn) which contains only 8 different integer values (from
>> 0 to 8).
> 
> An index as unselective as that is almost useless.  It's not surprising
> that the planner doesn't think it's worth the trouble to use it.

OK, thanks for pointing this out.
I was advised the PostGis list to use a multicolumn index on both 
the integer column and the geometry column.
Another suggestion was to cluster the table on the gist-geometry 
index.
What do you think about that ?

Regards
--
Arnaud


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