Chris and Tobias, thanks!
I did not test much with both layers in PostGIS since moving data into
the database temporarily was not possible solution. A quick local tests
shows "Creating spatial index" even then and yes both layers have
spatial indexes in the database. :O
"Manually" doing a server-side query instead of using QGIS' processing
tools was not an option. If it is, of course that would be the most
efficient approach.
Cheers, Hannes
On 4/17/25 07:42, Tobias Schula via QGIS-User wrote:
On Thursday, 17 April 2025, 07:36:51 CEST Johannes Kröger (WhereGroup) via
QGIS-User wrote:
Workaround, that works well in my specific data and use case:
My input layer only covers small and local parts of the full coverage of
the big PostGIS layer. Because of this I could switch the overlay input
for the intersection from the PostGIS layer to a query layer that
filters the PostGIS layer against the convex hull of the input layer
with ST_Intersects. Now only a small fraction of the features will be
fetched and the complexity depends mostly on the spatial distribution of
the input data, not the overlay layer.
Works very well so far and vastly faster.
I still feel like I am overlooking something very basic though :o)
Is your PostGIS read-only? Otherwise you could load your local layer into the
database and have your intersection done by the database. Should be way faster
and you won't download the whole coverage layer. Some time ago there was an
effort to map QGIS tools to their PostGIS equivalent and have the operations
run in the database directly instead of locally. But I think it stalled and I
didn't follow it anymore.
Best Regards
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Johannes Kröger / GIS-Entwickler/-Berater
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https://wheregroup-shorts.de
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