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Thread: alter system appending to a value

alter system appending to a value

From
Luca Ferrari
Date:
Hi all,
as trivial as it sounds, is there a smart way to use ALTER SYSTEM to
append to a value?
Something like: ALTER SYSTEM shared_preloaded_libraries =
current_setting( 'shared_preloaded_libraries' ) || ',foo';

Rationale: I'm using ansible to configure, thru different steps,
PostgreSQL instances and I would like to have every part to append its
configuration on the previous one.

Thanks,
Luca

Re: alter system appending to a value

From
Victor Yegorov
Date:
ср, 30 апр. 2025 г. в 14:15, Luca Ferrari <fluca1978@gmail.com>:
as trivial as it sounds, is there a smart way to use ALTER SYSTEM to
append to a value?
Something like: ALTER SYSTEM shared_preloaded_libraries =
current_setting( 'shared_preloaded_libraries' ) || ',foo';

I would do smth like:
SELECT format( 'ALTER SYSTEM SET shared_preload_libraries = %L;', setting )
  FROM pg_settings WHERE name = 'shared_preload_libraries' \gexec

Of course, you should add new value to the existing setting, making sure there are no duplicates and the format is correct.

--
Victor Yegorov

Re: alter system appending to a value

From
Greg Sabino Mullane
Date:
On Wed, Apr 30, 2025 at 7:15 AM Luca Ferrari <fluca1978@gmail.com> wrote:
Rationale: I'm using ansible to configure, thru different steps,
PostgreSQL instances and I would like to have every part to append its
configuration on the previous one.

Ansible is good for bringing your systems to a known consistent state, so your best bet would be to maintain the list of libraries inside Ansible and then simply apply it. If you really don't know what might be in the database, I would have Ansible read the current value, build the new one if the desired library is not there, and apply the new value.

Cheers,
Greg

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