Charlie Savage wrote:
The 2 point could be spatially equal given different SRIDS and
coordinates if they were projected to a common SRID. So should
geometry operators silently Call st_transform to make the righthand
match the lefthand before comparing? This would be quite the
expensive operation.
No. You can't automatically transform between different SRID values
Think of the case of one geometry with an SRID value of 4326 and one
with an SRID value of -1 (no coordinate system).
Exactly.
So different SRID values, then the geometries are not equal.
No -- as Stanley said, the geometries could be in fact equal, but
expressed in different SRS. So if ST_Equals() returned False, it would
be wrong.
It is up to the user to transform geometries to the same SRID before
calling ST_EQUALS.
Exactly. ;)
Reid
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