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Date: Wed, 10 Dec 2025 22:57:51 -0300
From: "Euler Taveira" <euler@eulerto.com>
To: "Chao Li" <li.evan.chao@gmail.com>,
 "Alvaro Herrera" <alvherre@alvh.no-ip.org>
Cc: japin <japinli@hotmail.com>, "Andres Freund" <andres@anarazel.de>,
 pgsql-hackers@lists.postgresql.org
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References: <202512091806.bsugq2l4wz7f@alvherre.pgsql>
 <1130A10B-E7AE-49F3-9E13-2CD69B3F9DFD@gmail.com>
Subject: Re: log_min_messages per backend type
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On Tue, Dec 9, 2025, at 11:00 PM, Chao Li wrote:
> Now =E2=80=9Cshow log_min_messages=E2=80=9D prints the raw string the =
user set, in=20
> above example, there is not a white-space between the two log levels,=20
> and =E2=80=9Cshow=E2=80=9D result doesn=E2=80=99t have a white-space b=
etween the two log levels=20
> either. IMO, =E2=80=9CSHOW log_min_messages=E2=80=9D should display a =
stable result, in=20
> other words, say =E2=80=9Cfatal, backend:log=E2=80=9D and =E2=80=9Cbac=
kend:log, fatal=E2=80=9D should=20
> show the same result as they are actually meaning the same. So, I woul=
d=20
> suggest normalize the raw string: put the general level in the first=20
> place and sort others by process type, then SHOW returns the normalize=
d=20
> string.
>

I thought about it but leave it alone because (a) it would increase this=
 patch
footprint and (b) the input might be different from the output. I could =
also be
done in another patch but under reflection an unstable output can break =
tests
or whatever uses the SHOW log_min_messages output. I thought this change=
 would
require a new show_log_min_messages to manipulate the input again but we=
 can
reassign the GUC value after sorting the existing list and creating a ne=
w string
list.

> In the =E2=80=9Cif=E2=80=9D and =E2=80=9Celse=E2=80=9D clauses, there =
are duplicate code to valid log=20
> levels. We should refactor the code to avoid the duplication. For=20
> example, pull up =E2=80=9Cloglevel=E2=80=9D to the =E2=80=9Cfor=E2=80=9D=
 loop level, then we can valid=20
> it after the =E2=80=9Cif-else=E2=80=9D.
>

The for loop is duplicate but if you create a separate function for it b=
ut the
result is:

 src/backend/commands/variable.c | 43 ++++++++++++++++++++++------------=
---------
 1 file changed, 22 insertions(+), 21 deletions(-)


I'll post a patch in a couple of hours after spend more time in it.


--=20
Euler Taveira
EDB   https://www.enterprisedb.com/