Re: BUG #19494: Error on transaction commit inside pipeline triggers psql's Assert

From: Michael Paquier <michael(at)paquier(dot)xyz>
To: Alexander Lakhin <exclusion(at)gmail(dot)com>
Cc: pgsql-bugs(at)lists(dot)postgresql(dot)org
Subject: Re: BUG #19494: Error on transaction commit inside pipeline triggers psql's Assert
Date: 2026-05-29 05:00:20
Message-ID: ahkdZJMZvyYlsfXK@paquier.xyz
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On Fri, May 29, 2026 at 07:00:01AM +0300, Alexander Lakhin wrote:
> it's happening upon/after postgres process termination, so PQgetResult()
> returns NULL, pset.piped_syncs == 1. I need more time to look deeper and
> to come with a reproducer, but maybe you can already see what's wrong.

Yeah, I do. Nice catch. See this sequence to reproduce the problem:
\startpipeline
INSERT INTO psql_pipeline_defer VALUES (1), (1) \bind \sendpipeline
\syncpipeline
SELECT pg_terminate_backend(pg_backend_pid()) \bind \sendpipeline
SELECT 1 \bind \sendpipeline
\endpipeline

When ending the pipeline the loop consuming the results is stuck, so
we could check the connection state. We are going to enter in a
freeze of the branches due to beta1 next week, so let's take our time.

Please feel to use the v2 attached for your tests. I am also testing
it more on my side.
--
Michael

Attachment Content-Type Size
v2-0001-psql-Fix-issues-with-deferred-errors-in-pipelines.patch text/plain 10.5 KB

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