Re: Instability in postgres_fdw regression tests

From: Nathan Bossart <nathandbossart(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: Instability in postgres_fdw regression tests
Date: 2026-02-10 17:58:23
Message-ID: aYtxv7h5gOuZW2sT@nathan
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On Tue, Feb 10, 2026 at 12:06:02PM -0500, Tom Lane wrote:
> It's not clear to me that it's worth running this to ground in any
> more detail than that. The behavior is not wrong; it's the test's
> fault to assume that these rows will be returned in a deterministic
> order. So I think the right fix is to adjust the test query,
> along the lines of
>
> -UPDATE ft2 SET c3 = 'bar' WHERE postgres_fdw_abs(c1) > 2000 RETURNING *;
> +WITH cte AS (
> + UPDATE ft2 SET c3 = 'bar' WHERE postgres_fdw_abs(c1) > 2000 RETURNING *
> +) SELECT * FROM cte ORDER BY c1;

+1. I faintly recall looking into this a while ago and, for some reason, I
was worried that this would become a game of Whac-A-Mole, so apparently I
didn't follow through. But fixing this query is still an improvement over
the status quo.

--
nathan

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