[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 suspected as much from the numbers.  Not sure where in the code it's
 doing it, but it seems the cached distance is returning the boundary
 distance rather than polygonal distance.  I recall somewhere in code
 seeing -- this is a polygon use  line tree algorithm. Can't remember where
 that was but I thought it a bit odd and thought there must be a switch
 somewhere else when computing to do area check but couldn't find it.


 {{{
 SELECT id , r, ST_Distance(condition_geo,geog) As  cached_dist
  , _ST_DistanceUncached(condition_geo,geog) As uncached_dist,--
 _ST_DistanceTree(condition_geo,geog),
 _ST_DistanceUncached(condition_geo,ST_Boundary(geog::geometry)::geography)
 As bound_dist
  from test_cache CROSS JOIN
    (SELECT 10*(1 + i*0.0001) As r, ST_Buffer(ST_GeogFromText('POINT(20.0
 30.0)'), 10*(1 + i*0.0001)) As geog
        FROM generate_series(320,324,1) As i) As foo
    WHERE id = 1;

  id |    r    | cached_dist | uncached_dist |    bound_dist
 ----+---------+-------------+---------------+-------------------
   1 | 10.3200 |           0 |             0 | 0.318550091945215
   1 | 10.3210 |  0.31954556 |             0 |  0.31954556026922
   1 | 10.3220 | 0.320541029 |             0 | 0.320541029428955
   1 | 10.3230 | 0.321536499 |             0 | 0.321536499026094
   1 | 10.3240 | 0.322531967 |             0 |  0.32253196740571
 }}}

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/2556#comment:8>
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