I have 3 SpatiaLite layers (one without geometry but with fields that need to be filtered, one with points and one with polygons, both without any non-geometry fields) that need to be combined to a single one, i.e. a left outer join is needed. Also, some filtering on the attributes needs to be done (in particular, a certain time range needs to be filtered). Apart from that, I also need to spatially filter the layers with points and polygons:
- All the points inside a certain boundary (a single polygon only available as a SHP) need to be retained
- All the polygons that overlap with this certain boundary need to be retained, i.e. both the polygons fully inside the boundary and also those which are only partially inside.
The main problem is that all of these layers contain quite a lot of data (i.e. >800mb) and it is quite tedious to trial-and-error the different possibilities. That is why I am asking what work process I should follow:
- Filtering and joining the SpatiaLite data with the Database manager in QGIS and then doing the clipping or whatever geometry function is needed for the above process? Could I actually do the clipping or whatever geometry function also directly in SpatiaLite, given that the boundary is only available as a SHP?
- Doing the clipping or whatever geometry function is needed first, which yields a shapefile, but how do I join them afterwards?
Actually, I am pretty lost / don't know the QGIS functions well enough.