Re: indexing lat lon - Mailing list pgsql-general

From Tom Lane
Subject Re: indexing lat lon
Date
Msg-id 14720.1088377460@sss.pgh.pa.us
Whole thread Raw
In response to indexing lat lon  ("Jonathan Raemdonck" <jonathan_raemdonck@hotmail.com>)
List pgsql-general
"Jonathan Raemdonck" <jonathan_raemdonck@hotmail.com> writes:
> These are the steps I take now:
> 1 'draw' a box around the lat/lon position we have as input
> 2 search the DB for all the points in this box
> 3 measure the distance to each point in the box

Right.  All you need is an index amenable to step 2.

> Is there a good way of indexing the lat/lon column so lookup is faster?

Yeah, you can store the lat/long as a point, build an rtree index on it,
and use box-overlap as the indexable operator.  I seem to recall that
you actually have to store the lat/long as a box of zero size to get
this to work with the present set of rtree-indexable operators.  If you
look in the archives you will find some previous similar cases.

            regards, tom lane

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