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
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.
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)
Any thoughts why PostGIS is about 40x slower than ArcMap at this
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...
Senior Technical Architect
Refractions Research, Inc.
postgis-users mailing list