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Re: geometry poligons performance and index

From: "Peter Koczan" <pjkoczan(at)gmail(dot)com>
To: giuseppe(dot)derossi(at)email(dot)it
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: geometry poligons performance and index
Date: 2007-09-05 02:58:02
Message-ID: 4544e0330709041958o3bd58974gf39f64ae083c81d6@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-admin
>  The results are ok, but the query is too slow. I tried to applay a GIST and
>  gtree index but performance did not improve.
>  By explaining the query I see that the where condition gets the query slow.
>  Is there a more simple way to check if two poligons have a not null
>  intersection (they overlap)?
>
>  Is there a kind of index I can use ?

If you stored the polygon geometries in the same table, you could use
a functional index (give the CREATE INDEX statement a function to
evaluate rather than a column). Check the CREATE INDEX page for
caveats. Beware that the index would grow with the square of the
number of rows if you did it like this.

Peter

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