[postgis-devel] [PostGIS] #378: Change ST_Equals to use && instead of ~=

[PostGIS]

#378: Change ST_Equals to use && instead of  ~=
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 Reporter:  robe     |       Owner:  pramsey      
     Type:  defect   |      Status:  new          
 Priority:  medium   |   Milestone:  PostGIS 1.5.0
Component:  postgis  |     Version:  trunk        
 Keywords:           |  
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 This is sort of getting to what Mark was saying.  The behavior is
 borderline wrong, but not for the reason I think Mark was complaining
 about.

 http://postgis.refractions.net/pipermail/postgis-users/2010-
 January/025551.html

 It is more an issue with soft upgrade.

 We can't change the behavor of ~= with soft upgrade because we can't drop
 operators.  That means people upgrading depending on which version they
 started off with are going to have some ~= with RECHECK and some with not
 RECHECK. Which will make it either behave like a bounding box equality
 check or a ST_OrderingEquals check.

 ~= with RECHECK is the wrong behavior for ST_Equals because a true or
 false to that answer doesn't tell you if _ST_Equals will be true or false.
 Because ST_EQUALS follows DE-IM which means geometries with flipped
 coordinates will be considered _ST_Equals, but fail the RECHECKED ~= and
 geometries that are invalid but binary equal can pass the ~= test but fail
 the _ST_Equals.

 Until we can figure out how to deal with the

 ~= inconsistent behavior of installs -- make this an && test.  Which will
 slow it down a bit I guess.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/378>
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