[postgis-users] Why PostGIS ST_Intersection much slower than ArcGIS Intersect ?

Jeff Lake jeff at michiganwxsystem.com
Thu Nov 29 06:14:40 PST 2012

Must have something to do with windows and or memory ..
I use ST_Intersects daily on a Linux Server (PostGIS 2.0, PG 9.1.6) with 
a quad core Xeon and 16gb memory
it takes milliseconds on much larger layers ..

*Jeff Lake*
MichiganWxSystem <http://www.michiganwxsystem.com>
AllisonHouse <http://www.allisonhouse.com>
GRLevelXStuff <http://www.grlevelxstuff.com>
On 11/28/2012 16:22, Étienne Desgagné wrote:
> Hello,
>     I don't want to denigrate PostGIS in any way and I know that my 
> comparison may be wrong but I'm trying to understand why a basic 
> ST_Intersection of two relatively small layers (< 1000 polygons) take 
> about 1m40 sec in PostGIS(2.0 on PG 9.2 on Windows) while applying the 
> ArcGIS Intersect on same layers and machine take about 2 sec?
> I'm aware of some PostgreSQL tuning settings but even applying basic 
> tuning recommendation for PostGIS I'm facing the same problem...
> My two layers also have a spatial index.
> Is it normal behavior? Any suggestion for reaching better performance?
> Note that I'm also using ST_Intersects on the join to filter only 
> intersecting features...
> Thanks a lot
> Etienne
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