[Qgis-user] Add application_name=QGIS to postgis connection string

[Jorge Gustavo Rocha]

Hi Toni,

It makes sense to have in all connections to the database. The 
application_name is already used by QGIS Server.

To have it in QGIS desktop (from core), a few edits must be made to make 
it happen. Maybe there are plug

Can you add this a new feature request?

Regards,

Jorge

On 30/06/22 10:47, Toni Schönbuchner via Qgis-user wrote:
> Hi all,
>
> my QGIS project is saved in postgres/postgis. The database instance 
> exists of 2 databases in
> replication mode (primary, hot standby). Where hot standby is 
> readonly. Before them pgpool2
> acts as a load balancer where /WRITE/ only goes to primary and 
> /SELECT/ queries go to both.
>
> My Problem now is, that QGIS uses
>
> SELECT pg_is_in_recovery();
>
> to detect if the database is readonly and if so, editing will be locked.
> Now whenever the connection is establish from the load balancer with 
> slave (as it sees a SELECT)
> QGIS thinks it cannot write, which is wrong in this situation.
>
> After advice from a pgpool2 developer I would now force all requests 
> coming from QGIS to primary
> only (and allow other clients like dbeaver to use the load balancing 
> feature.).
>
> The way to do this on side of pgpool2 is to catch the application name:
> app_name_redirect_preference_list = 'QGIS:primary'
>
> I can further already see that QGIS sets a var in postgresql logs.
>
>
> Connection matched pg_hba.conf line 94: "host all all 10.201.249.4/32 
> scram-sha-256
> 2022-06-30 09:54:40.056 CEST [822446] toni at spatial_db LOG:  statement: SET application_name='QGIS'
>
>
> The problem here is, that this var is set _after_ the connection is 
> established,
> where I need to set it in the „startup packet“.
>
> My question is, is there some way to tell QGIS to use a connection 
> string like:
> postgresql://10.201.249.2:5432/spatial_db*?application_name=QGIS*
>
> Or by use of some environment variable?
>
>
> Thanks a lot for any help,
>
> Toni
>
>
>
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