[postgis-users] finding duplicate value for the_geom field

[Obe, Regina]

I guess since everyone else is giving their suggestions I might as well
give one too

SELECT the_geom, min(gid) as min_gid, max(gid) as max_gid, COUNT(gid) as
numdupes
FROM sometable
GROUP BY the_geom
HAVING COUNT(gid) > 1


Note that the above query is a bit flawed since I think when you do a
group by on the_geom it actually does a group by on the bounding box
(not the geometry) and returns the first geometry.

I could be wrong though, but that is my understanding.

If you only have 2 dupes, min_gid and max_gid will return the potential
dupes

then you can compare them with a 

g1.the_geom = g2.the_geom  (I think does a binary compare) 

Hope that helps,
Regina



-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
Antonio Di Marco
Sent: Tuesday, May 27, 2008 7:57 AM
To: postgis-users at postgis.refractions.net
Subject: [postgis-users] finding duplicate value for the_geom field

Hi, how can I find duplicate value in a PostgreSQL table for the 
geometry field (the_geom)
Thanks a lot

Antonio

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