[postgis-devel] GEOS <-> PostGIS

[Obe, Regina]

Paul,

Those were probably my moans you were hearing.  For now I was just going to focus on its penalty as far as
doing unions with larger numbers of geometries and try to prove Mark wrong? that its faster to just convert everything over to GEOS first and then do all the unioning there.   Instead of convert to geos, union, convert to geos, union.

Looks like I'll have to at least touch the GEOS capi interface to test this theory out.

On a side note - I noticed the OSGEO homepage is still listing geos under geos.refractions.net and I can't get to any refractions sites at the moment for some reason.  Could be just my internet connection.

Thanks,
Regina





-----Original Message-----
From: postgis-devel-bounces at postgis.refractions.net on behalf of Paul Ramsey
Sent: Sat 8/23/2008 11:53 PM
To: PostGIS Development Discussion
Subject: [postgis-devel] GEOS <-> PostGIS
 
I saw an entry bemoaning the cost of this conversion (not that, in the
grand scheme, it's that much, we have bigger performance fish to fry
still). If we really want to go after it with a baseball bat, there is
the CoordinateSequence interface (not sure how it's implemented on the
C++ side) which should allow us to construct a GEOS geometry with a
pointer into the PostGIS geometry.  A much lighter approach than the
current PostGIS<->EWKB<->GEOS twice-copying route, but certainly with
some extreme care required in the implementation.

P.
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