[postgis-users] Spatial Join Performance

Paul Ramsey pramsey at refractions.net
Thu Nov 16 14:26:01 PST 2006


You could replace your Contains(A,B) with
Distance(A,B) < 0.001, which will run a shorter calculation faster 
(until we add a short-circuit to Contains()).

Otherwise your query looks pretty good. If your tables are relatively 
constant, clustering them will speed things up marginally, and make sure 
you've increased your PgSQL settings above the (tiny tiny) defaults.


Eric Shuman wrote:
> Paul,
> Your analysis of my scenario is correct. Most tax lot polygons are small and
> relatively simple compared to the zone polygons.  Though in some cases the
> lots can be big and cover more than one zone.
> So is the query I am using correct or is there something I can add to work
> around this issue?
> Thanks for the help!
> ---------------
> Eric Shuman
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