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

[Groene Bij]

Hi Richard,

I am definitely complicating things, that is so me 😊

But, are you now saying there is a relation between popstgresql client version and postresql server version? Because Nyall Dawson said there are unrelated.
Or, are both of you actually trying to say to me 'it doesn't matter that much, it will work'. Because I know it does work. Qgis3.16 with postgresql client 11.5 does work with postgresql server 12.x and potsgis 3.1 I am 'just' wondering if there are best matches.

And I will test the DB manager issue following your three steps and put the result in the github issue. It has to be something within the total package of qgis, because I have not made changes to my postgresql server version and postgis version.

Jeroen Hovens


-----Oorspronkelijk bericht-----
Van: Richard Duivenvoorde <rdmailings at duif.net> 
Verzonden: donderdag 4 februari 2021 11:02
Aan: Groene Bij <mail at groenebij.nl>
CC: '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

On 2/4/21 10:16 AM, Groene Bij wrote:
> 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?)

Hi Jeroen,

I think you are complicating things :-)

There are postgres/gis SERVER versions
And postgres/gis/ CLIENT LIBRARY version

In general: IF you have a SERVER version you should try to have the same CLIENT (=library) version.
BUT: only to be able to do the new things introduced in the SERVER version OR to have a better client version because they fixed bugs in that client(library) version.
In general: you can probably also connect to a new SERVER version with an older CLIENT (unless off course you want to do things that at the time of the CLIENT version was just not possible).

My guess: your issue above has anything to do with the pg client libraries used, or the combi server/client.
Chances are bigger that either QGIS is now running other SQL queries OR the logic (of loops for example) in QGIS has changed.

If you really want to know:
- enable logging in postgresql so you can see all queries the QGIS is sending
- check if there are differences
- run the same queries from withing pgsql on the server and do timing there.

Else we try to find a simple solution ("just use the right version") for a rather complex performance issue, which can have it's cause on many (other) levels... :-)

Groetjes,

Richard Duivenvoorde