[postgis-tickets] [PostGIS] #2556: geography ST_Intersects results depending on insert order

[PostGIS]

#2556: geography ST_Intersects results depending on insert order
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 Reporter:  gekorob                               |       Owner:  pramsey      
     Type:  defect                                |      Status:  new          
 Priority:  high                                  |   Milestone:  PostGIS 2.1.2
Component:  postgis                               |     Version:  2.1.x        
 Keywords:  st_intersects intersection geography  |  
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Comment(by robe):

 I take back what I said about this being different from the issue I posed
 in #2422.  i think there is something screwy with the
 circ_tree_distance_tree (or circ_tree_distance_tree_internal ) function.

 When comparing for the above case why the _st_distancetree gives the right
 answer while cached_dist is wrong, I discovered that _st_distancetree does
 a 2 pronged:

 {{{
 if ( CircTreePIP(circ_tree1, g1, lwgeom2) || CircTreePIP(circ_tree2, g2,
 lwgeom1) )
 }}}


 CircTreePIP test so since one PIP returns true, it never gets to the
 circ_tree_distance for this particular case.  If I add another prong to
 the geography_distance_cache function, it too returns 0.

 I also tried removing the tree_cache use in geography_distance_cache (just
 building the tree from scrach in both) similar to what the
 geography_distance_tree does, and it still returns the wrong same answer.
 So it does seem to be the tree logic here at fault in both bug tickets and
 cache is probably fine.

 I think that may also explain why for buffer below 10.00 the answer is 0
 as expected because the CircTreePIP kicks out before you get the
 circ_tree_distance_tree test.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/2556#comment:7>
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