[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:  closed             
  Priority:  medium   |   Milestone:  PostGIS 1.5.3      
 Component:  postgis  |     Version:  1.5.X              
Resolution:  wontfix  |    Keywords:  GEOMETRY hash UNION
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Comment(by vince):

 Of course I can't alone state that. I was attempting to implement some
 kind of steepest descent algorithm into a single recursive SQL query; was
 thinking also about identifying areas potentially liable to flooding by
 growing iteratively around water polygons until a certain z was reached. I
 guess this is far to be a major use of PostGIS.

 There is, of course, a workaround: do not include the geometry column in
 the result table (the one that grows iteratively), and, at each stage,
 perform a join between the result table and the table containing geometry
 info (using a primary key, for example). The query is more complex but,
 if, as you say, writing a hash function is tricky and maybe also
 cumbersome, it might even be more efficient to go that way.

 Anyhow, thanks a lot for your input and time.

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/1014#comment:7>
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