[postgis-devel] Is there a reason we don't have an ST_Intersection aggregate function

Komяpa me at komzpa.net
Tue Sep 2 04:59:45 PDT 2014

There's another thing with ST_Intersection/ST_Difference: sometimes you
have to make ST_Difference(geom, (select ST_Union(..,) where ...)) while
second operand evaluates to NULL (you shouldn't crop geometry). Currently
that leads to ST_Difference pushing out NULL. for my use case, that's not
desired semantics - can it be changed?

2014-09-01 4:16 GMT+03:00 Paragon Corporation <lr at pcorp.us>:

> I wasn't sure if we just thought there wasn't much utility in it or if
> there
> was a technical obstacle.
> I would think that would be easier to build than the other aggregates since
> as you add more geometries it shrinks and the current aggregate state is
> always the result of the previous state plus new geometry (so no need for
> an
> accumulation function or a final state function) and if you ever end up
> with
> a  geometry collection, you short-circuit out.
> Thanks,
> Regina
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Darafei "Komяpa" Praliaskouski
OSM BY Team - http://openstreetmap.by/
xmpp:me at komzpa.net mailto:me at komzpa.net
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