[postgis-users] spatial index for topology?

[Rémi Cura]

Hey,

For me face are slower because the geometry is computed each time, where
lines and points geometry are just retrieved from tables.
I agree using big topology is currently difficult.
Another trick is called "clipping": use a polygon to define the area you
are interested in and use spatial test to limit the number of objects to
load.

QGis is far from supporting correctly Postgis layer, even with simple
table/view .
For the tickets : http://hub.qgis.org/issues/8852 about one of the numerous
bug.
Nonetheless, latest dev version of QGis supports materialized view :
http://hub.qgis.org/issues/8791 , QGis developers are very reactive.

For the option it's in the rendering settings.

Sadly I'm not a QGis guru, but I'm often in the place where I have to use
it to do something it was not intended to do (like rendering mult-millions
point cloud).


I'm a wiki noob, can you provide me a link to create a new page (logged
with my osgeo loggin, I couldn't find the button to add a new page)
http://trac.osgeo.org/postgis/wiki/UsersWikiMain

This page looks also out of date?
Cheers,

Rémi-C




2013/10/28 Sandro Santilli <strk at keybit.net>

> On Mon, Oct 28, 2013 at 09:48:25AM +0100, Rémi Cura wrote:
> > Hey,
> > in QGIS you will have slow visualization essentially on faces.
> >
> > If your topogeom are based on node or edge it is faster.
>
> Any topogeometry layer is slow with QGIS, as it cannot use
> an index in any case.
>
> > If not, I use materialized view (requiere postgres 9.3), as a "buffer"
> for
> > qgis. The problem is QGIS 2.0 doesn't support yet materialized view, so
> you
> > have to create a proxy view onto your materialized view for qgis!
> > It is a bit of useless code but it is a great comfort gain.
>
> Interesting tip. Why doesn't QGIS support materialized views ?
> Sounds like a possibly very easy thing to add, did you file a ticket
> in there ?
>
> > Also, you can use QGis visualisation settings to make the element appears
> > dynamically, again this is better than just waiting with blank screen
>
> Ohh, lots of good info here. How do you do that ?
> Hey, what about writing some of these tips into the postgis wiki ?
> "Working with topology in qgis"
>
> --strk;
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