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

Thu Dec 15 00:06:12 PST 2022

Regina!
I am not a big expert in QGis and PostGIS.
Maybe I'm doing something wrong?
Either I load the rasters wrong in PostGIS, or I connect them incorrectly
in QGis?

ср, 14 дек. 2022 г. в 20:26, Regina Obe <lr at pcorp.us>:

> 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.
>
>
>
> *From:* postgis-users [mailto:postgis-users-bounces at lists.osgeo.org] *On
> Behalf Of *Alex German
> *Sent:* Wednesday, December 14, 2022 1:36 AM
> *To:* PostGIS Users Discussion <postgis-users at lists.osgeo.org>
> *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 <lr at pcorp.us>:
>
> 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:postgis-users-bounces at lists.osgeo.org] *On
> Behalf Of *Alex German
> *Sent:* Tuesday, December 13, 2022 4:12 AM
> *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>:
>
> [image: image.png]
>
> SRID in postgis 4326
>
> [image: image.png]
>
> SRID in QGis 4326
>
>
>
>
>
> вт, 13 дек. 2022 г. в 12:05, Bo Victor Thomsen <
> 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>:
>
> 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] *On
> Behalf Of *Alex German
> *Sent:* Monday, December 12, 2022 11:34 PM
> *To:* PostGIS Users Discussion <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
>
> 8-905-86-00-416
>
>
>
>
> --
>
> Алексей Герман
>
> 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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