[postgis-users] PostGIS 1.3.3 on Windows XP Unstable

Martin Davis mbdavis at refractions.net
Thu Aug 14 16:29:55 PDT 2008

> Yes, Java2D was able to perform a union on the geometries produced by
> ST_SimplifyPreserveTopology() and it does the union relatively fast. 
> The only thing I have found that beats Java2D is ArcGIS. In one test I
> did I performed a union of the USGS state boundaries
> (http://www.census.gov/geo/cob/bdy/st/st00shp/st99_d00_shp.zip). Here
> are the results:
> Oracle 11.1:	25 min
> PostGIS 1.3.3:	42 sec
> Java2D 1.5:		4 sec
> ArcMap 9.2:		1 sec
I just tried this in JTS via JEQL.  Timing for the union was 4 sec.
> Any thoughts why PostGIS is about 40x slower than ArcMap at this
> operation?
As Regina said, the current union operation in PostGIS is quite 
inefficient.  It should speed up a lot once the CascadedUnion algorithm 
is implemented (which is what the above test in JTS uses)

ArcMap's time is impressive...  since they're not open-source it's hard 
to know what they're doing to get this kind of speed.  8^)

> Any thoughts why Oracle takes 25 min? lol

Maybe for a truer metric you should multiply the time by the annual 
license fee  8^)  Of course, this doesn't help Oracle much...

Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022

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