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From: vignesh C <vignesh21@gmail.com>
Date: Wed, 17 Dec 2025 15:37:09 +0530
Message-ID: 
 <CALDaNm0gX2D6fD5yur-R5gagA7+AfLmLZU5Z8+tgjo61b-Y01w@mail.gmail.com>
Subject: Re: [Proposal] Adding Log File Capability to pg_createsubscriber
To: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
Cc: Gyan Sreejith <gyan.sreejith@gmail.com>,
	"pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>,
 Peter Smith <smithpb2250@gmail.com>
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On Tue, 16 Dec 2025 at 12:31, Hayato Kuroda (Fujitsu)
<kuroda.hayato@fujitsu.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