[postgis-users] Another Question on PostGIS Performance

[Thomas Haechler]

Jan,

I now prepared 3 layers in my mapfile for testing. Switching them on and
off seperately I found:

- DATA [shapefile] :
	8 secs to render
- DATA the_geom from veg:
	13 secs to render
- DAta the_geom from ( select map.the_geom, data.pg,
       map.gid from veg as map, veg_atr as data where map.pg
       = data.pg) as foo using unique gid :
	15 secs to render

The shapefile takes rather long, too. I guess I didn't realize this
before because I had always switched the rosa applet on, which takes
longer to draw. So maybe if you give me some tips on how to clean up the
data, this might be the solution.
Thank you,
Thomas



Jan Hartmann wrote:
> 
> Thomas,
> 
> It has nothing to do with indexes or joins. On rereading the mail you
> sent me personally I saw that even a simple DATA statement
> 
> DATA "the_geom from veg"
> 
> took more than 10 seconds. This certainly is far too slow for the number
> of lines you mentioned and could be a problem of the underlying map
> (digitizing errors?). To test this, you could try to use the original
> shapefile with MapServer. If this takes about as much time, you probably
>   have to clean up your data. If not, perhaps the people from
> Refractions would be interested in comparing this shapefile with the
> much slower PostGIS version.
> 
> Regards,
> 
> Jan Hartmann
> Department of Geography
> University of Amsterdam
> jhart at frw.uva.nl
> 

-- 

THOMAS HAECHLER

Geographic Information Systems Division
Institute of Geography
University of Zurich
Switzerland

thomas.haechler at geo.unizh.ch