Feedback-ID: i0fe9450f:Fastmail
Date: Tue, 22 Apr 2025 09:06:20 +0900
From: Michael Paquier <michael@paquier.xyz>
To: "a.kozhemyakin" <a.kozhemyakin@postgrespro.ru>
Cc: Daniel Verite <daniel@manitou-mail.org>,
	Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>,
	Jelte Fennema-Nio <postgres@jeltef.nl>,
	PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: Add Pipelining support in psql
Message-ID: <aAbdfKU2ZWeuAnIG@paquier.xyz>
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On Mon, Apr 21, 2025 at 03:22:28PM +0900, Michael Paquier wrote:
> Anyway, I don't think that there is much we can do under a
> PGRES_FATAL_ERROR in this code path when discarding the pipe results.
> As far as I can tell, the server has failed the query suddenly and the
> whole pipeline flow is borked.  The best thing that I can think of is
> to discard all the results while decrementing the counters, then let
> psql complain about that like in the attached.  I've added two tests
> in TAP, as these trigger a FATAL in the backend so we cannot use the
> normal SQL route, so as we have some coverage.
>=20
> @Anthonin: Any thoughts or comments, perhaps?  A second opinion would
> be welcome here.

While considering more ways to test this patch, I've recalled that
injection points that issue a FATAL in the backend to emulate the
original failure with more query patterns can provide more coverage,
and the discard cleanup is showing stable enough as presented in the
patch.  I am wondering if we could not be smarter with the handling of
the counters, but I really doubt that there is much more we can do
under a PGRES_FATAL_ERROR.
--
Michael

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