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List: postgis-users
Subject: Re: [postgis-users] Greetings, and road data questions
From: Andy Turk <andy () streetlight ! com>
Date: 2002-10-18 20:59:44
Message-ID: 1034974785.19217.59.camel () shadow
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On Fri, 2002-10-18 at 12:58, Paul Ramsey wrote:
> Andy, could you re-elabourate on your multi-key experiment? In summary,
> to do multi-key indexes with PostGIS, you need for all your indexes to
> be GiST-based. The pgsql native btree cannot be multi-key'ed with a GiST
> index. So you have to use the contrib/btree_index package and then build
> a multi-key GiST-only index. At the end of the day, did this work?
Correct. GiST will do multi key indexes, but I don't think there's a set
of character operators for GiST yet. So you have to "coerce" character
data into numerical form. I believe I used the operators that come with
btree_gist in the contrib directory.
I just went back and re-read my original posting on the subject from
June:
http://postgis.refractions.net/pipermail/postgis-users/2002-June/001154.html
I misremembered things a little. The multikey index was indeed faster
than a geometry index and a sequential scan. However, the "faster"
version was still taking 10 seconds or so for a single query and I
needed nearly instantaneous responses for an interactive application.
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