Determining which QGIS layer has spatial index

Question

I would like to loop over all layers within a QGIS project and determine which layer don't have a spatial index and cause QGIS to slow down.

I tried the method hasSpatialIndex() but this always returns SpatialIndexUnknown even if it's for example a shapefile with qix file present in the same folder (created from QGIS itself).

source = iface.activeLayer()

if source.hasSpatialIndex() == QgsFeatureSource.SpatialIndexNotPresent:
    print("not present")
elif source.hasSpatialIndex() == QgsFeatureSource.SpatialIndexUnknown:
    print("unknown")
elif source.hasSpatialIndex() == QgsFeatureSource.SpatialIndexPresent:
    print ("present")
else:
    print ("something else")

I guess it's a bug that QGIS does not recognize the qix files in the same folder where the shapefiles are stored?

Is there really no PyQGIS-method to check layers if they are indexed? I am pretty sure that QGIS itselfs checks the existence of a spatial index because it uses the spatial index automatically if it exists.

Answer 1

QGIS is able to check if the layer has spatial index or not for several providers, including shapefiles.

I've create a new project with two shapefiles. For one, I've created a spatial index. Then I used the GUI and PyQGIS to check if the index is correctly detected and reported.

GUI: Check layer properties

Layer properties panel will tell if the layer has spatial index or not.

For this shapefile layer, since a spatial index exists, the option "Create Spatial Index" is disabled (and a label Spatial Index Exists is used).

For another layer, the spatial index does not exist.

PyQGIS

If the GUI is showing the correct information, PyQGIS will do the same. You can test with this tiny script.

layers = QgsProject.instance().mapLayers().values()
for layer in layers:
    if (layer.dataProvider().hasSpatialIndex() == 1):
        print( f'The {layer.name()} has no spatial index' )
    if (layer.dataProvider().hasSpatialIndex() == 2):
        print( f'The {layer.name()} has a spatial index' )

Running this is writing the following output:

The madeira_com_indice has a spatial index
The madeira_sem_indice has no spatial index