[postgis-devel] [PostGIS] #520: No check for different srid on operators when index is used

[PostGIS]

#520: No check for different srid on operators when index is used
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  Reporter:  nicklas  |       Owner:  pramsey      
      Type:  defect   |      Status:  new          
  Priority:  medium   |   Milestone:  PostGIS 1.5.2
 Component:  postgis  |     Version:  1.5.X        
Resolution:           |    Keywords:               
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Comment (by mcayland):

 Right. This is likely because your tables tbl1 and tbl2 have no
 overlapping regions. When returning an index scan from an operator,
 PostgreSQL simply reads the bounding boxes from the index and returns them
 for use within the query - so in other words they don't go through the
 main operator function. We don't store the SRID in the bounding box since
 it is redundant information, i.e. for most use cases the SRID for a whole
 table should be the same and so it ends up just taking space.

 IMO having the actual operator functions in lwgeom_gist.c is misleading
 because they are not just used from within the index code which is
 probably where your confusion comes from.

 Originally we had the RECHECK operator which would trap this case, but
 since it has been demonstrated to contribute a significant overhead to
 several types of query it has now been removed.


 HTH,

 Mark.

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/520#comment:2>
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