[postgis-devel] [PostGIS] #1014: GEOMETRY type is not "hashable"

[PostGIS]

#1014: GEOMETRY type is not "hashable"
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 Reporter:  vince                |       Owner:  pramsey      
     Type:  defect               |      Status:  new          
 Priority:  medium               |   Milestone:  PostGIS 2.0.0
Component:  postgis              |     Version:  1.5.X        
 Keywords:  GEOMETRY hash UNION  |  
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 It seems the GEOMETRY type is not hashable, which prevents recursive WITH
 clauses to work with the UNION keyword:

 {{{
 WITH RECURSIVE path (id, the_geom, z) AS (SELECT id, the_geom, z_min AS z
 FROM "bâti" WHERE z_min = (SELECT MAX(z_min) FROM "bâti") UNION SELECT
 "bâti".id, "bâti".the_geom, z FROM path, "bâti" WHERE ST_Distance
 ("bâti".the_geom, path.the_geom) < 20 AND "bâti".z_min > path.z - 10)
 SELECT * FROM path;
 ERROR:  could not implement recursive UNION
 DETAIL:  All column datatypes must be hashable.
 }}}

 Using UNION ALL instead of UNION works, but produces duplicates.

 I have no clue on how to make the GEOMETRY type hashable, but if it is
 just providing a hash function, it might maybe worth it?

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/1014>
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