[postgis-users] PostGIS 1.3.3 on Windows XP Unstable

[Paragon]

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: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] 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

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