[QGIS-Developer] PostGIS Raster loading extrem long in QGIS 3.16 and 3.22

[Pascal Bircher / Netzwerk Schweizer Pärke]

Dear QGIS-Developer
I am working on a test-server (RAID6) implementing PostgreSQL/PostGIS with vector and raster support. The aim is a big database sharing different data types including high resolution (0.5m, also 0.1m; 8 bit; 3 bands) rasters and (2m, also 0.5m; 32bit floating point; 1 band) rasters.

For QGIS 3.16 and 3.22 I can report the following issue.
When I try to add a PostGIS raster with 32 bit floating point and a resolution of 2m into QGIS the query SELECT ST_SummaryStatsAgg() needs a lot of time at least 10-20 minutes on database.

Another interesting aspect I observed is that QGIS 3.10.4 loads the same raster nearly instantly.

I do not understand why a postgis-raster needs 10-20min to load in QGIS 3.16 and 3.22 and QGIS 3.10.4 does not run the above mentioned query on the database.

Kind regards

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Pascal Bircher
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