QGIS » QGIS Application

Running QGIS 3.2.0-Bonn on MacOS Mojave, though this has been a consistent problem since QGIS 2.x.

I run queries against a PostGIS database that is only accessible via VPN or SSH tunnel. For example, I set up a tunnel like this:

ssh -N -L 55432:db-hostname:5432 server

and then have a QGIS PostGIS connection named "DBTunnel" to localhost, port 55432.

Every time I follow these steps:

1. Create a layer with a PostGIS query to DBTunnel
2. Disconnect the ssh tunnel
3. Perform any action that would cause a DB query, like toggling that layer (I believe, but am not positive, that this step is required to reproduce)
4. Reconnect the ssh tunnel (say, after opening my laptop in a new location)
5. Perform a new query, and successfully see the result rows in the DB Manager window
6. Attempt to add those results as a new Layer

Then I get the following result:

1. The layer is not created
2. I see the following message in the PostGIS tab of the Log Messages panel:
   

   2018-10-19T10:30:49     WARNING    Unable to execute the query.
                The error message from the database was:
                no result buffer.
                SQL: SELECT * FROM (SELECT row_number() over () AS _uid_,* FROM (SELECT id, geometry from table) AS _subq_1_
                ) AS "subQuery_0" LIMIT 1
   

After this happens, the only way I know of to load new PostGIS layers is to restart the application, which as you can imagine is quite frustrating.

QGIS version info:
QGIS version 3.2.0-Bonn
QGIS code branch Release 3.2
Compiled against Qt 5.9.3
Running against Qt 5.9.3
Compiled against GDAL/OGR 2.2.4
Running against GDAL/OGR 2.2.4
Compiled against GEOS 3.6.2-CAPI-1.10.2
Running against GEOS 3.6.2-CAPI-1.10.2 4d2925d6
PostgreSQL Client Version 9.6.6
SpatiaLite Version 4.4.0-RC0
QWT Version 6.1.3
QScintilla2 Version 2.10.3
PROJ.4 Version 493