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

[Paul Ramsey]

It's normal, assuming that some of your geometries are quite large. If
someone wants to fund a "prepared intersection" development task I'm
sure we could make it 10x-40x faster.

P.

On Thu, Nov 29, 2012 at 10:04 AM, Étienne Desgagné
<etienne.desgagne at roche.ca> wrote:
> It take millisecond to me to when using ST_Intersects on a spatial join.
> What take much longer is when using ST_Intersection in the SELECT clause to
> effectively “clip” a layer with the other one…
>
>
>
> My computer run under Windows 7 64bits with dual core 2.70GHZ and 8 Go RAM.
>
>
>
> Is there anything I can do to check if it’s normal behavior on this platform
> or if something may be wrong on my installation?
>
>
>
> Thanks
>
>
>
> Etienne
>
>
>
> De : postgis-users-bounces at lists.osgeo.org
> [mailto:postgis-users-bounces at lists.osgeo.org] De la part de Jeff Lake
> Envoyé : 29 novembre 2012 09:15
> À : postgis-users at lists.osgeo.org
> Objet : Re: [postgis-users] Why PostGIS ST_Intersection much slower than
> ArcGIS Intersect ?
>
>
>
> 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
> AllisonHouse
> GRLevelXStuff
>
> 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
>
>
>
>
> _______________________________________________
>
> postgis-users mailing list
>
> postgis-users at lists.osgeo.org
>
> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>
>
>
>
> _______________________________________________
> postgis-users mailing list
> postgis-users at lists.osgeo.org
> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>