[postgis-users] Qgis + PostGis. Low operating speed.

[Jakob Lanstorp]

Also note there are issues and memory leaks with the PG raster reader in QGIS.

See https://github.com/qgis/QGIS/issues/47815

Jakob


From: postgis-users <postgis-users-bounces at lists.osgeo.org> On Behalf Of Alex German
Sent: Tuesday, December 13, 2022 10:12 QGIS
To: PostGIS Users Discussion <postgis-users at lists.osgeo.org>
Subject: Re: [postgis-users] Qgis + PostGis. Low operating speed.

QGis does not pick up overviews.
Separately, overviews are loaded very quickly.
I.e. if I load o_16_t6 in qgis, then the download speed is excellent.
In the properties of the table, there are overviews.

вт, 13 дек. 2022 г. в 12:29, Alex German <gr1047 at gmail.com<mailto:gr1047 at gmail.com>>:
[image.png]
SRID in postgis 4326
[image.png]
SRID in QGis 4326


вт, 13 дек. 2022 г. в 12:05, Bo Victor Thomsen <bo.victor.thomsen at gmail.com<mailto:bo.victor.thomsen at gmail.com>>:

Is the rasters in same projection (CRS) as the QGIS project ?

Med venlig hilsen / Best regards



Bo Victor Thomsen
Den 13-12-2022 kl. 07:50 skrev Alex German:
I did everything as described in the documentation.
raster2pgsql -I -C -e -Y -F -s 4326 -t 128x128 -l 2,4,8,16,32 "d:\Temp\060 tiff\res\t1.tif" testrastr.t1 | psql.
The download is very slow.
https://youtu.be/LULngZIs4nc

вт, 13 дек. 2022 г. в 09:45, Regina Obe <lr at pcorp.us<mailto:lr at pcorp.us>>:
PostGIS raster sadly doesn’t use the pyramids in the Tifs.  Or if it does no one told me.

You should build raster overviews using the raster2pgsql –l switch.
https://postgis.net/docs/using_raster_dataman.html#RT_Raster_Loader


Doc example is this which builds a level 2 and 4 pyramid

raster2pgsql -I -C -e -Y -F -s 26986 -t 128x128  -l 2,4 bostonaerials2008/*.jpg aerials.boston | psql -U postgres -d gisdb -h localhost -p 5432

QGIS knows how to use the overviews built that way and should be much faster to view in QGIS

raster2pgsql -s 4326 -t 256x256 -C -I -F "d:\Temp\060 tiff\res\OCG_t1.tif" OCG_t1 -R| psql.


From: postgis-users [mailto:postgis-users-bounces at lists.osgeo.org<mailto:postgis-users-bounces at lists.osgeo.org>] On Behalf Of Alex German
Sent: Monday, December 12, 2022 11:34 PM
To: PostGIS Users Discussion <postgis-users at lists.osgeo.org<mailto:postgis-users at lists.osgeo.org>>
Subject: [postgis-users] Qgis + PostGis. Low operating speed.

Hello everyone!
I have a GeoTIFF.
I built the pyramids in an external file using GDAL
"gdaladdo d:\Temp\060 tiff\res\t1.tif -r lanczos -ro 2 4 8 16 32 64 128 256 512.
Uploaded to PostGIS using
raster2pgsql -s 4326 -t 256x256 -C -I -F "d:\Temp\060 tiff\res\OCG_t1.tif" OCG_t1 -R| psql.
The number of files is more than 1000.
When trying to load tables in QGis, the loading is very slow.
At the same time, downloading to QGis from files is fast. Question. What is not configured correctly and how to speed up the download to Qgis from PostGIS?

--
Alex German

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Алексей Герман
8-905-86-00-416


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Алексей Герман
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Алексей Герман
8-905-86-00-416
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