[postgis-users] st_union returning null on various (valid) setsof polygons/multipolygons

[Paragon Corporation]

Giovanni,
You sure its null?  Did you do a IS NULL check on it?

If you are using PgAdmin III for example it may appear empty if its too
large to show. 

Leo 
http://www.postgis.us

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of G.
Allegri
Sent: Tuesday, June 22, 2010 4:13 AM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] st_union returning null on various (valid)
setsof polygons/multipolygons

I forgot to say, I'm working on Windows XP, Postgresql 8.4.4, Postgis 1.5.0

2010/6/22 G. Allegri <giohappy at gmail.com>:
> I'm trying to apply ST_Union on a set of geometries (multypolygons, 
> most of which containing a single geometry), to test the CascadedUnion 
> performance, but the most of times it returns a null result. I haven't 
> been able to find a rule: sometimes it seems to be the number of 
> geometries, sometimes the order, etc.
> Could someone replicate it? Here is a small selection of my layer (it 
> contains already validated geometries):
> http://www.giovanniallegri.it/share/postgis_selection.zip
>
> thanks a lot,
> Giovanni
>
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