Re: [Proposal] Adding Log File Capability to pg_createsubscriber

On Tue, 16 Dec 2025 at 12:31, Hayato Kuroda (Fujitsu)
<kuroda(dot)hayato(at)fujitsu(dot)com> wrote:
>
> Dear Gyan,
>
> +1 for the idea. This point has already been discussed since the initial commit
> [1], but it has left till now. I'm happy if you can take initiative.
> Of course I can review your patches.
>
> Per my understanding, pg_upgrade puts logfiles at the directory, under
> "${PGDATANEW}/pg_upgrade_output.d/${timestamp}". See Note part in [2].
> I feel more straightforward way is to follow that approach:
>
> 1. pg_createsubscriber creates a directory pg_createsubscriber_output.d/${timestamp}.
> ${timestamp} has the same format as ISO 8601 (%Y%m%dT%H%M%S).
> 2. pg_craetesubscriber saves outputs under the directory.
> 3. Outputs can be retained when the command failed or --retain is specified.
> Otherwise, they are removed at the end.

If I recall correctly, this was implemented that way earlier, but the
approach was abandoned around [1]. The primary reason was that when
users take a backup of the data directory, they would need to
explicitly manage the exclusion of this data, which was considered
undesirable.

> Are there benefits to provide -l option?

By providing this as an option, users can store the log files outside
the data directory, eliminating the need for any additional handling
during backups.

[1] - https://www.postgresql.org/message-id/d546c4bb-92d1-4e2d-898f-48234b12ed25%40app.fastmail.com

Regards,
Vignesh