Il 14/12/22 16:25, Regina Obe ha scritto:
That’s a bummer. You know how long that has been? I recall it
working when postgis raster access from QGIS was more or less a
straight connection to GDAL. I think that changed in the past 2-3
years or so.
Hi,
PG raster QGIS data provider was merged in 2019, it does use overviews
except when there is a SQL where condition in the layer definition, if
it doesn't it is a bug.
See: https://github.com/qgis/QGIS/issues/47815
Relevant parts:
https://github.com/qgis/QGIS/blob/master/src/providers/postgres/raster/qgspostgresrasterprovider.cpp#L2340
https://github.com/qgis/QGIS/blob/master/src/providers/postgres/raster/qgspostgresrasterprovider.cpp#L403
*From:*postgis-users [mailto:[email protected]]
*On Behalf Of *Alex German
*Sent:* Wednesday, December 14, 2022 1:36 AM
*To:* PostGIS Users Discussion <[email protected]>
*Subject:* Re: [postgis-users] Qgis + PostGis. Low operating speed.
Thanks, Regina! On the Qgis forum, I was told that overviews from
PostGIS to Qgis do not work.
ср, 14 дек. 2022 г. в 09:02, Regina Obe <[email protected]>:
That comes as a big surprise to me. It’s been a while since I’ve
used QGIS on raster, but last time I tried it was able to read the
overview tables.
I know there was a time not too long ago when QGIS was revising
how it queries PostGIS raster. I forget what that revision was
about, if it was just changing how it used GDAL to query PostGIS
or getting rid of GDAL in some cases.
So this might have caused an issue with its reading of overviews.
I’ll try to test this out with latest QGIS in sometime this or
next week to verify what the issue is here.
Thanks,
Regina
*From:*postgis-users
[mailto:[email protected]] *On Behalf Of *Alex
German
*Sent:* Tuesday, December 13, 2022 4:12 AM
*To:* PostGIS Users Discussion <[email protected]>
*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 <[email protected]>:
image.png
SRID in postgis 4326
image.png
SRID in QGis 4326
вт, 13 дек. 2022 г. в 12:05, Bo Victor Thomsen
<[email protected]>:
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 <[email protected]>:
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:[email protected]] *On
Behalf Of *Alex German
*Sent:* Monday, December 12, 2022 11:34 PM
*To:* PostGIS Users Discussion
<[email protected]>
*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
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8-905-86-00-416
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Алексей Герман
8-905-86-00-416
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Алексей Герман
8-905-86-00-416
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--
Alessandro Pasotti
w3: www.itopen.it
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