[postgis-users] Nitpicking on empty geometries

[Rolf A. de By]

Greetings all,

My st_intersection() of two multipolygons returns an empty geometry: no 
problems, as it should.  When I ask for its st_geometrytype() I am told 
it is "ST_Geometry", and I can live with that.  When I ask for its 
st_astext() I get "GEOMETRYCOLLECTION EMPTY," and that by itself I can 
also live with.  However, in combination I find those answers 
inconsistent and potentially confusing for writing geometry manipulation 
code.  And also, isn't the OGC standard SF99 demanding that geometry 
collections always have at least one member geometry?  Or am I missing 
something here?

Rolf


International Institute for Geo-Information Science and Earth Observation (ITC)
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