[postgis-tickets] [PostGIS] #4736: ST_NumGeometries is zero for GeometryCollection with empty parts

[PostGIS]

#4736: ST_NumGeometries is zero for GeometryCollection with empty parts
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  Reporter:  Mike Taves  |      Owner:  strk
      Type:  defect      |     Status:  closed
  Priority:  medium      |  Milestone:  PostGIS 3.2.0
 Component:  postgis     |    Version:  main
Resolution:  fixed       |   Keywords:
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Comment (by mdavis):

 Replying to [comment:5 pramsey]:

 > I'm half-tempted to go with num geometries is 1 for simple objects and n
 -sub-geometries for any collection, even a collection of empties, and make
 the behaviour consistent. Would require updates to the wiki page, but I
 think the angels on the pin dance better that way. Thoughts?

 FWIW, that is the semantics that JTS implements.  It allows seamless
 iteration over atomic and collection geometries, with no special cases.
 OGC only defines ST_NumGeometries and ST_GeometryN on GeometryCollection
 and subclasses.  IMO it's nicer to have functions operate on any geometry
 type in a consistent way (especially in a language like SQL, where it's
 awkward to handle special cases, and NULL has a semantic slightly
 different to EMPTY).  This seemed like the right way to extend them to
 atomic geometries.

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Ticket URL: <https://trac.osgeo.org/postgis/ticket/4736#comment:12>
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