Horton

Re: Possibility to disable `ALTER SYSTEM`

Jelte Fennema-Nio <postgres@jeltef.nl>

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From: Jelte Fennema-Nio <postgres@jeltef.nl>
To: Gabriele Bartolini <gabriele.bartolini@enterprisedb.com>
Cc: Peter Eisentraut <peter@eisentraut.org>, Tom Lane <tgl@sss.pgh.pa.us>, "David G. Johnston" <david.g.johnston@gmail.com>, Magnus Hagander <magnus@hagander.net>, Robert Haas <robertmhaas@gmail.com>, Martín Marqués <martin.marques@gmail.com>, Isaac Morland <isaac.morland@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2024-02-07T13:49:01Z
Lists: pgsql-hackers

Commits

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

  1. Add allow_alter_system GUC.

  2. Rename COMPAT_OPTIONS_CLIENT to COMPAT_OPTIONS_OTHER.

  3. Remove support for version-0 calling conventions.

On Wed, 7 Feb 2024 at 11:35, Gabriele Bartolini
<gabriele.bartolini@enterprisedb.com> wrote:
> This is mostly the approach I have taken in the patch, except allowing to change the value in the configuration file.

(I had missed the patch in the long thread). I think it would be nice
to have this be PGC_SIGHUP, and set GUC_DISALLOW_IN_AUTO_FILE. That
way this behaviour can be changed without shutting down postgres (but
not with ALTER SYSTEM, because that seems confusing).

> but wasn't sure in which `config_group` to place the 'enable_alter_system` GUC, based on the src/include/utils/guc_tables.h. Any thoughts/hints?

I agree that none of the existing groups fit particularly well. I see
a few options:

1. Create a new group (maybe something like "Administration" or
"Enabled Features")
2. Use FILE_LOCATIONS, which seems sort of related at least.
3. Instead of adding an "enable_alter_system" GUC we would add an
"auto_config_file" guc (and use the FILE_LOCATIONS group). Then if a
user sets "auto_config_file" to an empty string, we would disable the
auto config file and thus ALTER SYSTEM.

I'd prefer 1 or 3 I think. I kinda like option 3 for its consistency
of being able to configure other config file locations, but I think
that would be quite a bit more work, and I'm not sure how useful it is
to change the location of the auto file.