AW: Re: [Qgis-user] QGIS mapserver performance

[Ziegler Stefan]

Hi Andi

> What exactly do you mean by "rendering straight from postgis"? What 
> software is rendering straight from Postgis? UMN Mapserver, or what 
> other renderer? Or your own renderer?
No, "straight from postgis" means adding the layer in QGIS from postgis.
I save this qgis project and make it available as WMS. Since there is
only QGIS (as renderer) involved I thought there would not be a big
performance difference. Ok, there is apache who is handling the cgi
request but that won't take 4 seconds.

> There are some performance bottlenecks regarding clipping of 
> larger/more 
> complex polygons. Marco can tell you more.
I don't think it's a clipping issue since it's fast when adding the same
layer 'straight from postgis' :) So there must be some additional work
when making a detour. 


regards
Stefan

> 
> Andreas
> 
> On 3/20/11 2:44 PM, Ziegler Stefan wrote:
> > Hi
> >
> > I have some questions concerning the performance of qgis 
> mapserver: Using layers with a small amount of polygons I do 
> not see a big difference between rendering the same layer 
> straight from postgis and from local qgis mapserver 
> installation. For a layer with some 400'000 polygons it takes 
> approx. 4 seconds from qgis mapserver (even for large scales 
> with only some polygons to render). But it only takes some 
> fractions of a second when the layer is rendered straight 
> from postgis (and growing with smaller scales ->  more polyons).
> >
> > Everything is running on a dual core laptop. So there 
> should be no big download bottleneck. No special styles are 
> applied to the layers (just a simple fill and an outline). 
> Are there some requests in addition to "GetMap"? Or what's 
> responsible for this big difference?
> >
> > regards
> > Stefan
> >
> > Mit freundlichem Gruss
> > Stefan Ziegler
> > Leiter amtliche Vermessung
> >
> > Amt für Geoinformation
> > Rötistrasse 4
> > 4501 Solothurn
> > 032 627 75 96
> > _______________________________________________
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> > Qgis-user at lists.osgeo.org
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