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Re: log_min_messages per backend type

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Chao Li <li.evan.chao@gmail.com>
Cc: Euler Taveira <euler@eulerto.com>, japin <japinli@hotmail.com>, Andres Freund <andres@anarazel.de>, pgsql-hackers@lists.postgresql.org
Date: 2026-02-09T12:40:51Z
Lists: pgsql-hackers 
On 2026-Feb-09, Chao Li wrote:

> While it’s reasonable to configure a full comma-separated list in
> postgresql.conf, it seems there’s currently no convenient way for a
> superuser to change the log level of a single process type. For
> example:
> 
> ```
> evantest=# alter system set log_min_messages='backend:debug4';
> ERROR:  invalid value for parameter "log_min_messages": "backend:debug4"
> DETAIL:  Default log level was not defined.
> ```
> 
> This feels a bit inconvenient in practice. Intuitively, it would be
> nice if setting a single type:level could be merged into the existing
> log_min_messages value, rather than requiring users to restate the
> entire configuration.

This has been discussed before and no satisfactory solution has been
found.  You're welcome to spend time thinking on this; see e.g.
https://postgr.es/m/20200928033924.GA998042@toroid.org where not only
the details were discussed, but also some links to other threads about
the same idea were given.

-- 
Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Cleanup for log_min_messages changes in 38e0190ced71

  2. Allow log_min_messages to be set per process type

  3. Assign "backend" type earlier during process start-up

  4. Use integer backend type when exec'ing a postmaster child

  5. Sort guc_parameters.dat alphabetically by name

  6. Create a separate file listing backend types

  7. Replace postmaster.c's own backend type codes with BackendType