[postgis-users] Topology newbie question - put in a triangle, get out a quad, minus the Z values

Sandro Santilli strk at keybit.net
Tue Dec 4 09:34:28 PST 2012

On Tue, Dec 04, 2012 at 12:14:47PM -0500, John Morrison wrote:
> First, thanks for the quick reply, which works like a champ!
> I apologize for the RTFM-able question in the first place.  I was obviously
> confused, as the "mbr" column (which I now understand to be the minimum
> bounding rectangle) was the only geometry column for the topology faces.  I
> also assumed qgis (which I am using) was correct in showing the faces as
> quads.  Whoops.
> So this brings me to my next question - is there some canonical,
> best-practices sort of way I can get a geometry column (as I currently have
> for for not only the topology nodes and faces, but for other GIS data in
> the database) that qgis and I will treat correctly?  Should I define some
> sort of view on the faces table and use (for both qgis and my own stuff)
> that layer instead?

If you're interested in face geometries you can have qgis load a query
extracting them for you. The db_manager qgis plugin contains a useful
topoviewer module that does the layer setup for you (you select a topology
schema and go to Schema->TopoViewer menu).

Unfortunately there's no way currently to instruct qgis about using the mbr
column for indexing, so if you have many faces it could be slow to load.


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