Re: [QGIS-Developer] PostGIS Raster loading extrem long in QGIS 3.16 and 3.22
Hi,
the reason for the different behavior is that the old QGIS version was
using GDAL to access PG rasters while the new versions uses a QGIS native
data provider which is using ST_SummaryStatsAgg() to calculate statistics,
I believe that this call can become very slow on large rasters and we
should probably reduce the time by using a smaller sample size but this has
to be implemented/fixed yet, feel free to file a ticket on the QGIS bug
tracker.
The good news is the you can still load the raster from QGIS using the GDAL
provider with a connection string that looks like this: "PG:
dbname={dbname} mode=2 host={host} port={port} table={table}
schema={schema} sslmode=disable"
Hope this helps.
Regards.
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[QGIS-Developer] PostGIS Raster loading extrem long in QGIS 3.16 and 3.22
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 --- Pascal Bircher ___ QGIS-Developer mailing list QGIS-Developer@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
