[postgis-users] Performance tuning PostGIS and understanding the explain statement

Benjamin Wragg bwragg at tpg.com.au
Tue Jun 17 15:38:04 PDT 2003

The features table is 88246 points and the regions is a collection of
polygon's like countries and continents. The region that I've been
testing is a polygon of Australia which is quite detailed. 

So from what your saying its using all the indexes correctly, but they
aren't much use as the distance calculation it does between each feature
and region is whats causing the problem? I use the distance

I'll send the data straight to your email account so the whole list
doesn't get it.



-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
David Blasby
Sent: Wednesday, 18 June 2003 1:40 AM
To: bwragg at tpg.com.au; postgis-users at postgis.refractions.net
Subject: Re: [postgis-users] Performance tuning PostGIS and
understanding the explain statement


It appears that you are doing about 5000 distance() calculations.  If 
your features and region polygons are quite complex, this could take an 
awfully long time.

Could you somehow send me your region2 and feature table and I can make 
a better guess as to why its so slow.


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