[postgis-devel] [PostGIS] #259: ST_Distance geography throws an error with empty geographies
PostGIS
trac at osgeo.org
Tue Oct 6 08:56:21 PDT 2009
#259: ST_Distance geography throws an error with empty geographies
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Reporter: robe | Owner: pramsey
Type: defect | Status: closed
Priority: medium | Milestone: postgis 1.5.0
Component: postgis | Version:
Resolution: fixed | Keywords:
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Comment (by mcayland):
That's a tricky one... Off the top of my head, I see this:
ST_DWithin(null, null) -> null
ST_DWithin(null, geometry) -> null
ST_DWithin(geometry, null) -> null
i.e. if any input parameter is null, the output is null
ST_DWithin(empty, geometry) -> false
ST_DWithin(geometry, empty) -> false
i.e. if any input parameter is a geometry (but empty) then the predicate
can never be true (because an empty geometry exists but has no area or
perimeter)
It would be nice to come up with a definitive reference for this, whatever
we choose, and put it up somewhere on the wiki.
ATB,
Mark.
--
Ticket URL: <http://trac.osgeo.org/postgis/ticket/259#comment:11>
PostGIS <http://trac.osgeo.org/postgis/>
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