[postgis-devel] ST_UnaryUnion vs ST_Dump + ST_Union

Jose Carlos Martinez Llario jomarlla at cgf.upv.es
Sun Oct 2 04:29:07 PDT 2011

Dear List,
┬┐What are the differences between an st_unaryunion and a normal union 
aggregate with the dump geometries from the geom?
I just could see that the order of the generated segments change.
What am I missing?

In order to node a LineString with selt-intersections, I still have to 
use st_union (point, geom) because st_unaryunion does not node 
self-intersection lines.
So I do not know if this new operator is very useful.
Probably Im missing things, I didnt check it out deeply.


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