Re: [postgis-users] PostGIS 1.3.3 on Windows XP Unstable

[Martin Davis]

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

_______________________________________________
postgis-users mailing list
postgis-users@postgis.refractions.net
http://postgis.refractions.net/mailman/listinfo/postgis-users