Re: Possibility to disable `ALTER SYSTEM`

On Wed, 7 Feb 2024 at 11:35, Gabriele Bartolini
<gabriele(dot)bartolini(at)enterprisedb(dot)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.