[postgis-users] nearest neighbor search

[Stephen Woodbridge]

If you computed the distance from some point (x,y) to all points in the 
table and sorted the results the first (or last) would be the nearest.

select point_id, Distance(...) as distance from mytable order by 
distance asc limit 1;

should give you the point_id and distance from (x,y). I'm still to much 
of a newbie to postGIS to fill in the exact syntax, if someone else can 
help. This can probably be accellerated greately if you can limit you 
search to some BBOX if you have lots of points.

-Steve

Robert Helmer wrote:
> Hello,
> 
> I have been trying to find info on how to do a "nearest neighbor"
> search on point data I have loaded into my PostGIS/PostgreSQL
> database.. the only thing I've found so far is messages in
> the archive of this mailing list, suggesting using Distance()
> and a temp table.
> 
> Does anyone have any pointers for how to do this? I'd sure
> appreciate it!
> 
> 
> Thanks,
> Rob Helmer
> 
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