Re: [Proposal] Adding Log File Capability to pg_createsubscriber

Thank you for the feedback everybody. As I read through this email chain, I
found differing opinions on how logging should be implemented. This
ambiguity leaves me unsure as to which solution(s) to pursue. As of right
now, I have attached the git-format patch like Hayato Kuroda recommended
(but it does not have any new changes). I am willing to implement whatever
solution when we reach a consensus.

Thank you for all of the help,
Gyan Sreejith

On Thu, Dec 18, 2025 at 1:49 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:

> On Thu, Dec 18, 2025 at 6:59 AM Euler Taveira <euler(at)eulerto(dot)com> wrote:
> >
> > On Wed, Dec 17, 2025, at 7:07 AM, vignesh C wrote:
> > >
> > > 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.
> > >
> >
> > Do we really need an option to capture the stdout / stderr output to a
> file? I
> > doubt it. There is already various ways to capture. psql and pg_upgrade
> are the
> > only tools that have this option.
> >
>
> pg_ctl also has the -l option. I think any place where long
> text/errors can be outputted, a log file is preferred because one
> could later parse it to know the exact details. Also, splitting the
> log as proposed here or in pg_upgrade helps to navigate the LOG like
> is the problem in start/stop of the server or a pub-sub setup?
> Similarly the log can be splitted for pub/sub specific information.
> There appears to be some useful information like:
>
> pg_createsubscriber: warning: two_phase option will not be enabled for
> replication slots
> pg_createsubscriber: detail: Subscriptions will be created with the
> two_phase option disabled. Prepared transactions will be replicated at
> COMMIT PREPARED.
> pg_createsubscriber: hint: You can use the command-line option
> --enable-two-phase to enable two_phase.
>
> I think it will be useful to LOG this separately from the main LOG [1]
> (which can contain server specific info as follows) so that users can
> consider running pg_createsubscriber with additional options or
> changing the subscriber configuration once setup is complete.
>
> [1]:
> [startup] LOG: database system was interrupted; last known up at
> 2025-12-17 14:46:07 IST
> [startup] LOG: starting backup recovery with redo LSN 0/06000028,
> checkpoint LSN 0/06000080, on timeline ID 1
> [startup] LOG: entering standby mode
> [startup] LOG: redo starts at 0/06000028
> [startup] LOG: completed backup recovery with redo LSN 0/06000028 and
> end LSN 0/06000120
> [startup] LOG: consistent recovery state reached at 0/06000120
>
> --
> With Regards,
> Amit Kapila.
>