Date: Mon, 31 Mar 2003 11:00:32 -0600
From: Bruno Wolff III <bruno@wolff.to>
To: Rajesh Kumar Mallah <mallah@trade-india.com>
Cc: Rudi Starcevic <rudi@oasis.net.au>, pgsql-sql@postgresql.org
Subject: Re: Off topic : world database
Message-ID: <20030331170032.GA2303@wolff.to>
Mail-Followup-To: Rajesh Kumar Mallah <mallah@trade-india.com>,
	Rudi Starcevic <rudi@oasis.net.au>, pgsql-sql@postgresql.org
References: <3E824070.7070207@oasis.net.au> <3E878C84.5030004@oasis.net.au>
	<200303311108.48751.mallah@trade-india.com>
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On Mon, Mar 31, 2003 at 11:08:48 +0530,
  Rajesh Kumar Mallah <mallah@trade-india.com> wrote:
> 
> I am wanting to make an application similar to you
>  which shud be able to  get all the places within certaint 
> radius of the place in  question.

If you look at contrib/earthdistance in the 7.4 source tree, there is
a varient way to use earthdistance based on the cube data type instead
of point. This varient uses a 3D representation so you don't have to
worry about issues at the poles or wrap around. You can do indexed
searches (though I don't really know how well (fast) the indexes work,
since I haven't tried them with large amounts of data) inside of
bounding boxes, then double check that the points are really closer
than the desired distance.

This varient uses a couple of new cube functions and check constraints
on domains. You can just comment out the check constraints. The 7.4
contrib/cube might work with 7.3. (If there are problems you should
be able to compare with the 7.3 version to figure out how to make it
work.)

P.S.

It would be nice if you eventually summarize your data sources, as I
would eventually like to get hold of similar data for areas outside of
the US for my project.