[postgis-devel] [PostGIS] #230: Put in costs in _ST and possibly other functions

[PostGIS]

#230: Put in costs in _ST and possibly other functions
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  Reporter:  nicklas  |       Owner:  robe                     
      Type:  defect   |      Status:  assigned                 
  Priority:  medium   |   Milestone:  postgis 1.5.0            
 Component:  postgis  |     Version:  1.4                      
Resolution:           |    Keywords:  st_dwithin st_expand bbox
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Comment (by mcayland):

 Yes, correct. The aim should be for us to pick defaults that "just work"
 for the majority of people rather than complicating matters by having to
 tune individual installations.

 I know from my work on the statistics side of PostGIS that it is a
 pointless exercise trying to perfect our estimates so that they are
 accurate to reality; this is mainly because the existing routines in
 PostgreSQL are only estimates too. All we need to do is ensure that the
 more expensive functions are weighted heavier than their cheaper
 equivalents by a reasonable amount of units so given a dead heat in terms
 of planner cost, it will always choose the cheaper function first.


 ATB,

 Mark.

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/230#comment:22>
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