[postgis-users] [!! SPAM] multipolygon to single polygon

Mehmet Erkek merkek at reidin.com
Thu Apr 26 08:22:55 PDT 2012

Hi Juilen, thanks for quick answer. 


I have 1 geometry and 1 row on the table. this geometry is multiploygon which consists of 4 polygons.

I want to convert this mutlipolygon to one single polygon..


Any idea how I can do this?

I hope it is clearer now.





From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of ju
Sent: 26 Nisan 2012 18:02
To: PostGIS Users Discussion
Subject: Re: [postgis-users] [!! SPAM] multipolygon to single polygon


not clear...

1) if you have 4 polygons in 4 rows table distinct, this is not a multi object issu. for  this case use
 dissolve to group polygone into only one, this is not a topic of dump.

2) if you have 1 geometry and 1 row on the tablme, so this is a multi object topic
you must sperate the differents objet of the collection

here : http://www.postgis.org/docs/ST_GeometryN.html

--Extracting all geometries (useful when you want to assign an id)
SELECT gid, n, ST_GeometryN(the_geom, n)
FROM sometable CROSS JOIN generate_series(1,100) n
WHERE n <= ST_NumGeometries(the_geom);

best regards, julien

Le 26/04/2012 16:27, Mehmet Erkek a écrit : 


I have multipolygons which I would like to convert a single polygon. is there a way to do this? please check the attached image. I tried st_dump and afterwards st_union , but eventually I get a multipolygon again, not polygon. 





Mehmet Erkek

www.REIDIN.com <http://www.reidin.com/>  


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