[postgis-users] Spatial join not finishing

[Jorge Gil]

Hi everyone,

I've been trying to do a spatial join for a couple of days in different 
ways and it never seems to finish. I've done something identical before 
in a much larger set of the same data and it worked after a few hours.

I have a polygons (buildings) table with 150,000 records and a points 
(land use) table with 170,000 records. I want to calculate how many 
points are within each building and add that total to the column 'units' 
in the buildings table. The query I run is this:

UPDATE buildings as aa SET units=bb.count FROM (SELECT cc.gid , count(*) 
from buildings as cc, landuse as dd
where ST_Within(dd.the_geom, cc.the_geom) group by cc.gid) as bb WHERE 
aa.gid=bb.gid;

I also try to create a separate table with the results of the join 
before doing the update, but the first step also fails.

Am I doing something wrong? Is there a simple trick that makes this more 
efficient?

Thank you,
Jorge

-- 
Jorge Gil
PhD Candidate

TU Delft / Faculty of Architecture
Department of Urbanism
Chair of Spatial Planning and Strategy

Julianalaan 134
2628 BL Delft
P.O. Box 5043
2600 GA Delft
The Netherlands

www.tudelft.nl