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List:       postgis-users
Subject:    Re: [postgis-users] PostGIS Capabilities
From:       Paul Ramsey <pramsey () refractions ! net>
Date:       2004-02-24 15:52:31
Message-ID: 74B57048-66E1-11D8-A7C2-000393D33C2E () refractions ! net
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On Tuesday, February 24, 2004, at 04:35 AM, Markus Schaber wrote:

> HIt seems that such distance operation queries still involve a 
> sequential
> scan over the whole table. So one better combines this query with an
> bounding box that is &&'ed to the geometries to make use of the index.

Yes, always.

> The same Problem appears when searching the nearest Object, PostGIS
> cannot make any use of spatial indices in this case, so one has to
> interate with growing bounding boxes...

Indexing a "nearest" query is quite a nasty business if you think about 
it.

P.


      Paul Ramsey
      Refractions Research
      Email: pramsey@refractions.net
      Phone: (250) 885-0632


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