[postgis-devel] [PostGIS] #408: Catch "Exception in LWGEOM2GEOS" in ST_IsValid
strk
strk at keybit.net
Thu Feb 4 13:30:09 PST 2010
I might be missing something, but wouldn't an exception
from LWGEOM2GEOS mean unambiguosly that the geometry
is invalid ?
... thinkin loud ... could also be an OOM actually ...
--strk;
On Thu, Feb 04, 2010 at 01:26:38PM -0800, Martin Davis wrote:
> Right, this has just been explained to me by our resident PostGIS expert
> Kevin. To repeat his explanation, the PostgreSQL language engine is
> auto-converting the string to a Geometry type, since that's what
> st_isvalid accepts. This is where the exception is happening - which
> means that it can't be caught inside st_isvalid.
>
> I would humbly suggest that it would be nice to be able to prevent C
> exceptions leaking out into the SQL world where possible. Perhaps a
>
> st_isvalid_safe(String geomWKT)
>
> could be provided to allow users to avoid this. (And since Kevin also
> pointed out that this doesn't allow distinguishing between Geometry and
> the new Geography type, a
>
> st_isvalid_geog_safe(String geogWKT)
>
> might be needed as well.
>
> Code it up and let the users vote with their keyboards!
>
> PostGIS wrote:
> >#408: Catch "Exception in LWGEOM2GEOS" in ST_IsValid
> >--------------------------+-------------------------------------------------
> > Reporter: ddegasperi | Owner: pramsey
> > Type: enhancement | Status: new
> > Priority: medium | Milestone:
> > Component: postgis | Version: 1.4.X
> >Resolution: | Keywords:
> >--------------------------+-------------------------------------------------
> >Comment (by pramsey):
> >
> > Non possible.
> >
> > The '':text entry first gets passed into the text parsing routines which
> > is where the failure actually occurs, not in st_isvalid. We have had
> > internal arguments many times about where validity checking should occur,
> > and the current situation is that trivially invalid geometries (1-point
> > lines, unclosed polygons) are failed during parsing.
> >
> > IMO, they shouldn't fail, but that's a personal opinion, not a consensus
> > one.
> >
> >
>
> --
> Martin Davis
> Senior Technical Architect
> Refractions Research, Inc.
> (250) 383-3022
>
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--
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