To get the distance in meters you can use the geography type instead.
something like:
SELECT *
FROM zip_polygon
WHERE ST_DWithin(geom::geography, ST_GeogFromText('4326;POINT(13.171982
52.52646)'), 2);
But to get it working fast you should store in geograpgy type and build
your spatial index n that.
HTH
Nicklas
On Tue, 2011-02-08 at 12:29 +0100, Marcel Kroschel wrote:
> hi @all.
> Hope someone can help me ;)
> I uses postgis 1.5.2., create a table with with multipolygon and lng/lat
> coordinates called zip_polygon
>
> SELECT AddGeometryColumn ( 'zip_polygon', 'geom', 4326, 'MULTIPOLYGON', 2 );
>
> When ich want all polygons in distance i use this query:
> SELECT *
> FROM zip_polygon
> WHERE ST_DWithin(geom, ST_GeomFromText('POINT(13.171982 52.52646)', 4326),
> 0.02);
>
> But the manual say, that the last entry is the distance in meter. When i
> replace the 0.02 to the value 1, then i get the whole list.
>
> example of geom - entry (SELECT (ST_AsText(geom)) from zip_polygon zp):
> "MULTIPOLYGON(((13.69375 50.82966,13.69252 50.83034,13.68925
> 50.83206,13.68766 50.83374,13.68639 50.83576,13.68399 50.83782,13.68235
> 50.8386,13.72514 50.81991)))"
>
> greeting
> Marcel
>
>
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