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Subject: Re: Environment variable to disable diffs file output
From: Daniel Gustafsson <daniel@yesql.se>
In-Reply-To: <ba567012-bff5-465a-8ee7-913b32f45d89@gmail.com>
Date: Mon, 6 Apr 2026 16:11:02 +0200
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>,
 postgres@jeltef.nl
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Message-Id: <E936A054-6975-480A-A355-9DB983F88484@yesql.se>
References: <ba567012-bff5-465a-8ee7-913b32f45d89@gmail.com>
To: =?utf-8?B?0JjQu9GM0Y8g0KfQtdGA0LTQsNC60L7Qsg==?=
 <i.cherdakov.pg@gmail.com>
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 <https://www.postgresql.org/message-id/E936A054-6975-480A-A355-9DB983F88484%40yesql.se>
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> On 6 Apr 2026, at 09:55, =D0=98=D0=BB=D1=8C=D1=8F =D0=A7=D0=B5=D1=80=D0=B4=
=D0=B0=D0=BA=D0=BE=D0=B2 <i.cherdakov.pg@gmail.com> wrote:

> I'd like to add a environment variable to the patch to
> disable diff output. Sometimes you have to be creative
> with exploratory testing, modifying test files, etc.,
> and multiple diff outputs can become a nuisance. This
> doesn't change the default behavior, but it does give
> you control over diff output in tests for specific
> scenarios where a large number of failures are expected
> (mass runs or exploratory testing with changing tests).
>=20
> The env usage and implementation are somewhat similar
> to PG_REGRESS_DIFF_OPTS
>     PG_REGRESS_DISABLE_DIFFS_OUTPUT=3D1 make check -s.
>=20
> For now, I suggest to simply disabling it, but I'm also
> considering passing the number of lines to output via env
> or via flag pg_regress instead of completely disabling it.
> Something like
>     PG_REGRESS_DIFFS_NUMBER_LINES_OUTPUT=3D20 make check
> and then when an error occurs, 20 lines will be output
> instead of the default 80. Setting it to 0 disables
> diffs output.

I'm not sure I entirely understand the problem.  If you expect lots of
failures, but also don't want to see the test failures, what is the use =
of
running the tests?  Why not run the subset you actually care about and =
expand
that set as testing fixes bugs/issues?

--
Daniel Gustafsson