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

G. Allegri giohappy at gmail.com
Tue Jun 22 01:04:01 PDT 2010

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):

thanks a lot,

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