[Qgis-user] What is postgresql client version and does it have anything to do with different postgresql versions

[Groene Bij]

Greg,
And list,

That is actually a very useful comment. First, because I did not realize
there could be different builds and that would mean the info screen within
qgis would show different values.
Secondly, because yes, I am using the installer for windows from qgis.org
and there are actually two of them, the osgeo4w and the standalone
installer, although I don't think there is any difference in the actual
build when choosing the same version number.

This might actually be the main reason for my questions.
I know qgis is build using different libraries and such and the whole idea
should be that I should not really care about it. When I download the LTR it
should work and it should work well with other programs.
However, since qgis is so dependent on other libraries and is very honest
and open in telling me this (the info screen), I get this feeling it could
also be 'sensitive' to other programs.
The same goes for postgresql and postgis. All of these programs are itself
dependent on and are build using different libraries, some of which are also
used in qgis (like geos, gdal/ogr). That's why I have this idea that some
combinations of versions might work better with each other. However, there
is very little information to be found on this subject.

Take this example: 
I would like to see DB Manager as just a shell or GUI which will work with
every postgresql and postgis version the same way, but in fact it isn't. I
found DB manager to work differently from qgis3.10 to 3.12 and above.
Something changed and as a result, simple select queries can take up 10 to a
100 times longer in qgis3.12 and up compared to qgis3.10
(see also https://github.com/qgis/QGIS/issues/40643)


So, I am mostly looking for some kind of reassurance. Things like: qgis3.16
will work fine with postgresql version a to d and postgis version f to l. Or
qgis will work fine with any postgresql above version x and postgis above
version y. I do realize these are difficult statements to make (how to test
them?)


Jeroen Hovens





-----Oorspronkelijk bericht-----
Van: Greg Troxel <gdt at lexort.com> 
Verzonden: woensdag 3 februari 2021 19:04
Aan: Groene Bij <mail at groenebij.nl>
CC: 'chris hermansen' <clhermansen at gmail.com>; 'qgis-user'
<qgis-user at lists.osgeo.org>
Onderwerp: Re: [Qgis-user] What is postgresql client version and does it
have anything to do with different postgresql versions


"Groene Bij" <mail at groenebij.nl> writes:

> Hence my search for information on dependencies and whether QGIS 3.16 
> (or later) favors any postgresql and postgis version above another

Probably not a useful comment to you, but as I understand the qgis sources
can be built against a number of postgresql client libraries.  I think you
are talking about, as I gather most windows users do, not just about qgis
sources but about binaries: particular distributions of already-built qgis.
There, I find "qgis 3.16 does x" to be a bit on shaky ground, as there could
be multiple such binaries even for Windows, and there are certainly various
builds for other systems.  You are probably talking about the installer on
qgis.org.