On 04/05/2016 10:20 AM, Sandro Santilli wrote: > On Tue, Apr 05, 2016 at 06:09:12PM +1000, Nyall Dawson wrote: > >> What's the topology issue you're hoping to solve with this? > > Topology face layers from the TopoViewer (via DBManager plugin) > use an expensive (and volatile, thus non-indexable) query to > generate the geometry to be used for display. The provider generally > applies the spatial filter to the geometry field, which in this case > is ineffective. > > I could fix this by adding the possibility to specify a > "spatial-filter-field" which is different from the "spatial-display-field" > (similarly could be done for obtaining the $area from the provider, > for example).
That would be nice. A possibility for this could be to allow compiling virtual fields which can make use of the expression variables. A function for the topo query could then be translated to a (server side) SQL query. The virtual field could be visualized via the geometry generator symbology. The missing pieces I see are * allow compiling virtual fields * expression compilation for functions * expression compilation for variables Matthias _______________________________________________ Qgis-user mailing list [email protected] List info: http://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
