RE: [Proposal] Adding Log File Capability to pg_createsubscriber

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.

Are there benefits to provide -l option?

Regarding the patch format, our community prefers patches generated by
git format-patch. Can you see the blogpost [3] and try to create patches based on the command?
One benefit is we can easily do versioning.

[1]: https://www.postgresql.org/message-id/60b45b8a-3047-4a21-ba2a-ddb15daa638f%40eisentraut.org
[2]: https://www.postgresql.org/docs/devel/pgupgrade.html
[3]: https://peter.eisentraut.org/blog/2023/05/09/how-to-submit-a-patch-by-email-2023-edition

Best regards,
Hayato Kuroda
FUJITSU LIMITED