[postgis-devel] [PostGIS] #1778: ST_CollectionExtract: inconsistent EMPTY results

[PostGIS]

#1778: ST_CollectionExtract: inconsistent EMPTY results
----------------------+-----------------------------------------------------
  Reporter:  strk     |       Owner:  pramsey      
      Type:  defect   |      Status:  closed       
  Priority:  medium   |   Milestone:  PostGIS 2.0.1
 Component:  postgis  |     Version:  2.0.x        
Resolution:  invalid  |    Keywords:               
----------------------+-----------------------------------------------------
Changes (by pramsey):

  * status:  new => closed
  * resolution:  => invalid


Comment:

 Actually the behaviour is consistent: when passed a non-collection, the
 function just echoes it back. This is true with both empties and non-
 empties.
 {{{

 postgis20=# select
 ST_AsText(ST_CollectionExtract('GEOMETRYCOLLECTION(LINESTRING(0 0, 1 1))',
 2));
          st_astext
 ----------------------------
  MULTILINESTRING((0 0,1 1))
 (1 row)

 postgis20=# select ST_AsText(ST_CollectionExtract('LINESTRING(0 0, 1 1)',
 2));
       st_astext
 ---------------------
  LINESTRING(0 0,1 1)
 (1 row)

 }}}
 The return for non-empty collections is always a homogeneous multi-
 something, even if the input collection has only one member.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/1778#comment:1>
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