[postgis-devel] [PostGIS] #1828: Estimate returned by geography_gist_selectivity results in slow query plan for ST_DWithin

[PostGIS]

#1828: Estimate returned by geography_gist_selectivity results in slow query plan
for ST_DWithin
---------------------------+------------------------------------------------
 Reporter:  realityexists  |       Owner:  mcayland     
     Type:  defect         |      Status:  new          
 Priority:  medium         |   Milestone:  PostGIS 2.0.2
Component:  postgis        |     Version:  2.0.x        
 Keywords:                 |  
---------------------------+------------------------------------------------

Comment(by pramsey):

 And so if you change the estimate for <const> && <const> to 1.0
 (geography_estimate.c:540), you get the correct estimate on our overall
 DWithin query.
 {{{
         /*
          * We are working on two constants..
          * TODO: check if expression is true,
          *       returned set would be either
          *       the whole or none.
          */
         if ( ! IsA(self, Var) )
         {
                 POSTGIS_DEBUG(3, " no variable argument ? - returning
 default selectivity");

                 PG_RETURN_FLOAT8(1.0);
         }
 }}}

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/1828#comment:34>
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