Re: BUG #18944: Assertion Failure in psql with idle_session_timeout Set

On Thu, Jun 12, 2025 at 12:35 AM Michael Paquier <michael@paquier.xyz> wrote:
> So my point would be to take a drastic decision in
> ExecQueryAndProcessResults() if we detect a PGRES_COPY_BOTH,
> PGRES_COPY_OUT or PGRES_COPY_IN while in a pipeline, and just give up.
> It does not prevent the feature to work for other queries, and we
> still have test coverage for queries that cannot run in transaction
> blocks like REINDEX CONCURRENTLY, etc.  It just means that we cannot
> enter in a COPY state while in a pipeline.

Agreed, I've also contemplated this option given the amount of edge
cases there are along with the limited usefulness of doing COPY within
a pipeline. In a sense, this worked as a way to show the missing bits
of libpq's pipeline support with COPY.

The attached patch now aborts the connection anytime we enter COPY
state while within a pipeline and removes all pipeline+COPY from the
SQL tests.