[QGIS-Developer] point in polygon strikes again: big performance issue

[Nyall Dawson]

On Mon, 15 Mar 2021 at 09:34, Jorge Gustavo Rocha <jgr at di.uminho.pt> wrote:
>
> Hi David,
>
> Thanks for replication this issue. "Join attributes by location
> (summary)" is definitely the best choice for this use case. It creates
> the new layer in a few seconds. That's why I think we are missing
> something (spatial indexes?, dependency graph?) in the expression engine.

Actually there's LOTS missing
- if you're not using the overlay_* method, then spatial indices won't
be used at all
- even if you use the overlay_* methods, the overlay tests are not
optimised in any way (they don't use prepared geometries), so will
always be orders of magnitude slower than the processing tools.

Nyall



>
> There are anomalies in the data. That's almost the same with any dataset
> we start working with :-)
>
> Regards,
>
> Jorge
>
> Às 21:47 de 14/03/21, David Strip escreveu:
> > I was able to replicate your problem on my system (Win 10, QGIS 3.10.5).
> >
> > I tried "Join attributes by location (summary)". This computed the
> > result in about 5 seconds.
> > There are some anomalies in the data, however. For example, there's an
> > entry for Belgium with province value "Unknown" and no lat/lon, so it
> > doesn't get included in the total. Also, the point for Northern
> > Territories, Australia, lies in the ocean, so it is not contained in the
> > Australia polygon.
> >
>
> J. Gustavo
> --
> Jorge Gustavo Rocha
> Departamento de Informática
> Universidade do Minho
> 4710-057 Braga
> Gabinete 3.29 (Piso 3)
> Tel: +351 253604480
> Fax: +351 253604471
> Móvel: +351 910333888
> skype: nabocudnosor
> _______________________________________________
> QGIS-Developer mailing list
> QGIS-Developer at lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer