[postgis-devel] Re: [PostGIS] #101: ST_Union on one-row table doesn't union

[PostGIS]

#101: ST_Union on one-row table doesn't union
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  Reporter:  pramsey   |       Owner:  pramsey      
      Type:  defect    |      Status:  assigned     
  Priority:  medium    |   Milestone:  postgis 1.4.0
 Component:  postgis   |     Version:  1.4          
Resolution:  accepted  |    Keywords:               
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Comment (by robe):

 Paul is this really a PostGIS problem or a GEOS one.  Not knowing c from a
 hole in the wall-- it seems we are recursing thru the polygons just to
 allocate enough space for a GEOS lwpoly.  So its GEOS that is not dealing
 with unioning a single multipolygon correctly.  Its probably assuming --
 its already one geometry why bother.

 I would have thought unioning with an empty geometry collection would
 solve the issue but doesn't seem too either -- get back the same dumb
 invalid multipolygon

 SELECT ST_OrderingEquals(ST_Union(ST_GeomFromText('GEOMETRYCOLLECTION
 EMPTY'),the_geom),the_geom) FROM testunion;

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/101#comment:10>
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