[postgis-devel] SP-GIST: what to do

Paragon Corporation lr at pcorp.us
Tue Sep 30 13:13:14 PDT 2014

I would say probably not worth pursuing.  KNN gist for geography is much
more useful of a pursuit I think :)


From: postgis-devel-bounces at lists.osgeo.org
[mailto:postgis-devel-bounces at lists.osgeo.org] On Behalf Of Paul Ramsey
Sent: Tuesday, September 30, 2014 2:45 PM
To: PostGIS Development Discussion
Subject: [postgis-devel] SP-GIST: what to do

Hey all,

So, I've now got a working sp-gist implementation


(Build and install, and after enabling postgis also run the commands in
gserialized_spgist_2d.sql to add the spgist functions and opclass)

This is a copy of the quadtree implementation Teodor put into PgSQL, but
bound to our 'geometry' type. It is also restricted to points only (though,
non-optimally, I cannot throw a "not a point" error until I get into the
picksplit routine, so it's possible to build a small index on non-point
features. just how to handle that corner case is something I have yet to
figure out).

The question is whether to continue to pursue this work for 2.2. Given the
lack of a "compress" hook for spgist, support for anything other than points
seems problematic. Similarly, the corner case above could have potentially
deleterious effects. Also, since we have a cast from geometry::point (for
geometries that are points), it's possible for people to build functional
spgist indexes *already*, if they like (though they won't have as good
stats/planning as geometry, since the spatial stats code in postgresql
proper is lacking)

I feel like the lack of support for all geometry variants, and the inability
to cleanly restrict the index to just a point variant in combination make
spending more effort on a direct geometry binding probably not worth it,
though I'm willing to entertain counter arguments.


Paul Ramsey 
pramsey at boundlessgeo.com 
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