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

[Étienne Desgagné]

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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