[Qgis-user] Dynamic Source Filtering in QGIS - How?

[Stefan Keller]

Dear all,

I would like to display only say the 50 most important features of a
layer in a QGIS project when I zoom out and in. Almost all features
have an attribute qrank starting at NULL or 1, and the larger qrank
is, the more "important" the object is. Here is a demo of the web app
https://castle-map.infs.ch/

You can set a filter by right-clicking on the layer, e.g. as follows:
SELECT * FROM “castles_etc_ranked_osm_2025” ORDER BY qrank DESC LIMIT 50;

The problem is that QGIS only applies this filter (and SQL) once (when
setting up the filter). However, I want QGIS to update this filter and
reapply it every time someone's zooming or panning.

I have looked in vain at the options for “Update Layer with notify” in
the layer menu in the “Display” tab. I also tried it with a view and
the file manager, but without success.

1. Can QGIS be configured this way? E.g. with Dynamic Provider Filter Plugin?
2. I think a small Python script (QGIS Python Console) could be
another solutions. But which signals would I need to intercept?

Yours, Stefan