[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
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 Reporter:  realityexists  |       Owner:  mcayland     
     Type:  defect         |      Status:  new          
 Priority:  medium         |   Milestone:  PostGIS 2.0.2
Component:  postgis        |     Version:  2.0.x        
 Keywords:                 |  
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Comment(by pramsey):

 The problem is that for <const> && <const> we're returning
 DEFAULT_SELECTIVITY, which is very high. So the <const> && <const> term is
 washing out the other one, the one we care about. As the comment in the
 code block notes, the <const> && <const> case should return either 0 or 1,
 depending on the actual evaluation of the statement, but not something in
 between. I'm wondering if returning 1 might actually be the path of "less
 harm" in a temporary hack, rather than returning DEFAULT_SELECTIVITY.

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/1828#comment:36>
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