[Qgis-developer] Improving rendering speed

[Martin Dobias]

On 3/20/06, Radim Blazek <radim.blazek at gmail.com> wrote:
> On 3/18/06, Martin Dobias <wonder.sk at gmail.com> wrote:
> > Hi,
> >
> > I've started to do some research on how to make rendering faster. My
> > benchmarks and thoughts on optimizing are on wiki:
> > http://wiki.qgis.org/qgiswiki/Rendering_Performance
>
> Nice! Thanks.
>
> | "First draw of newly loaded GRASS layer takes cca double time to complete
> | (is there any caching happening?)"
>
> I am not sure, geometry is not chached, it is always read from file.
> It could be building of spatial index which is build on first
> call to select(QgsRect *rect, bool useIntersect)
> but 1.5s seems to be too fast to build spatial index for 30000 lines.
> It sould be also simply system file cache.

Hm, I wouldn't say that system file cache does so big difference -
with layers from OGR provider nothing like this happens. Actually it
might be that building spatial index is that fast - I have tried it
again, adding and removing testing layer several times in a row,
always with the same results, that's why I don't think that system
cache is reason of such difference on every load.

> PostGIS is running on the same machine? Connected via TCP/IP
> or socket file?
> The files are all on local disk?

Yes, database is on the same machine and files only from local disk
(classical parallel ATA with Ultra DMA turned on).

My PostrgreSQL listens on both unix socket and TCP/IP socket, but it
seems that QGIS uses only TCP/IP connections (I watched netstat
output). Is there any way to override it to use unix socket?

Martin

>
> Radim
>
>
> > I'd like hear some feedback from you!
> >
> > Bye,
> > Martin
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