fix query hang in Jetbrains programs (IntelliJ, DataGrip, etc)

[Mause]

Fixes #8489
Fixes #7631

[carlopi]

Very much not my area, but what happens if returnsChangedRows is set, so at least logically there is work to be performed?

Say a CREATE TABLE t AS SELECT .... some lengthy calculation;.
This I think returnsNothing but still might not be trivial.

[Mause]

Very much not my area, but what happens if returnsChangedRows is set, so at least logically there is work to be performed?

Say a CREATE TABLE t AS SELECT .... some lengthy calculation;. This I think returnsNothing but still might not be trivial.

If returnsChangedRows is set, returnsNothing will not be set - they are exclusionary