Would something like this be inefficient? I store data in a geometry
type, as I don't really care about the spheroid accuracy, as my
location queries are mostly less than 30 km apart. So...
SELECT ST_AsGeoJSON(location), title, description
FROM event
WHERE ST_DWithin(location::geography,
ST_GeogFromText('POINT(-83.359752 42.5212687)'),4000)
ORDER BY ST_Distance(location,
ST_GeomFromText('SRID=4326;POINT(-83.359752 42.5212687)'))
I cast geom to geog and perform st_dwithin and order by proximity.
Ilya
On Tue, May 11, 2010 at 8:37 AM, Emilie Laffray
emilie.laff...@gmail.com wrote:
On 11 May 2010 07:34, Malm Paul paul.m...@saabgroup.com wrote:
Hi,
I have a database stored in WGS84 EPSG:4326
I would like ti find objects within a distance from a lat/lon point.
1) If i use 1 degree as the distance, will I then get an eliptic search
area?
2) Will i find objects on the other side of the Datum shift border if I
enter a point like lat=60°, lon= -179,5° with a distance of 1°?
3) Hov do I enter a lat/lon point and a distance in meters?
If you want to do something that works but is relatively inefficient for 3,
you can do the following:
ST_DWithin() AND ST_DistanceSphere() distance in meters
Of course, you would have to make sure that the search radius is big enough
to correspond to your search in meters. Of course, it works only for points
due to ST_DistanceSphere.
If you want to perform something with any geometry, look at postgis 1.5 and
the new geography type.
Emilie Laffray
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