Mike, FWIW: The unioning operations currently in PostGIS are very inefficient.
We are working on improving the union operation in PostGIS and hopefully will have at least a first draft to show in the next release. Most notably porting the JTS logic for doing Cascaded Unions to PostGIS. This from the looks of it will probably improve the union operation 10-fold and in cases where PostGIS would just fall apart when doing large union operations, it will complete within a reasonable time. As Martin said, would be nice if you could post your samples, and then we can test out with our new algorithms for doing unioning. I've been testing with samples here and there, but the more the merrier. Thanks, Regina -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Martin Davis Sent: Thursday, August 14, 2008 6:03 PM To: PostGIS Users Discussion Subject: Re: [postgis-users] PostGIS 1.3.3 on Windows XP Unstable It's your bad luck to have geometries that make PostGIS fail... 8^) If there's geometries which cause problems with certain operations, the most helpful thing to do is to post them along with a description of the problem. That gives a fighting chance to fix them when further development is done. So Java2D worked on your problem? I have to admit, I'm impressed how robust Java2D is. If I could understand their algorithm I'd be keen on trying to follow their approach to get the same level of robustness in JTS/GEOS... Bresnahan, Mike wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA256 > > Welp, I think I have given up on trying to do the union inside PostGIS > because I can't make it fast and reliable. Instead I have decided to > use Java2D to perform the union. I ended up doing the same thing with > Oracle. Both Oracle and PostGIS have been bad at doing CAG operations > when compared to Java2D and ESRI ArcGIS. Is that just my bad luck or > is there something fundamental going on here? > > > -- 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 _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users