From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | David Cottingham <david(dot)cottingham(at)cl(dot)cam(dot)ac(dot)uk> |
Cc: | pgsql-sql(at)postgresql(dot)org |
Subject: | Re: Indexing a field of type point |
Date: | 2007-08-09 17:33:27 |
Message-ID: | 17550.1186680807@sss.pgh.pa.us |
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Lists: | pgsql-sql |
David Cottingham <david(dot)cottingham(at)cl(dot)cam(dot)ac(dot)uk> writes:
> I have a table containing a field named location, of type point, i.e. a
> position in two dimensions. The table has several million records in, and I
> need to extract those records whose location value is contained within a
> certain bounding box.
Given the standard opclasses, your best bet is to convert the point into
a zero-volume box or circle, eg
create index i on t using gist (circle(pointcol,0))
and then express queries as "circle(pointcol,0) overlaps target-box".
PostGIS might have something more nicely adapted ...
regards, tom lane
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