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From: shveta malik <shveta.malik@gmail.com>
Date: Thu, 19 Feb 2026 09:35:03 +0530
Message-ID: <CAJpy0uCi4DNz_NxqsFMY_u_Kfq8+o0J2gk0w0v6X3Mrf0MuL9A@mail.gmail.com>
Subject: Re: [PATCH] Support automatic sequence replication
To: Peter Smith <smithpb2250@gmail.com>
Cc: Ajin Cherian <itsajin@gmail.com>, Ashutosh Sharma <ashu.coek88@gmail.com>, 
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Amit Kapila <amit.kapila16@gmail.com>, 
	shveta malik <shveta.malik@gmail.com>
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On Thu, Feb 19, 2026 at 3:26=E2=80=AFAM Peter Smith <smithpb2250@gmail.com>=
 wrote:
>
> On Wed, Feb 18, 2026 at 9:05=E2=80=AFPM shveta malik <shveta.malik@gmail.=
com> wrote:
> >
> ...
> > 3)
> > I noticed that copy_sequences is invoked twice per sync cycle=E2=80=94o=
nce for
> > sequences in the INIT state, and once for sequences in the READY state
> > to detect drift. This means we ping the primary twice during each sync
> > cycle. We should consider combining this logic into a single
> > copy_sequences call. Since we already have the state information
> > (INIT, READY, etc.) for each local sequence, copy_sequences can
> > internally check the current state and decide whether to transition a
> > sequence to READY based on its previous state. This approach would
> > allow us to fetch all required information from the primary in a
> > single call.
> >
> > I also think that we do not even need to mention the states here and
> > we can give a single message instead of 2:
> > DEBUG:  logical replication sequence synchronization for subscription
> > "sub1" - for sequences in INIT state batch #1 =3D 5 attempted, 5
> > succeeded, 0 mismatched, 0 insufficient permission, 0 missing from
> > publisher, 0 skipped, 0 no drift
> > DEBUG:  logical replication sequence synchronization for subscription
> > "sub1" - for sequences in READY state batch #1 =3D 5 attempted, 0
> > succeeded, 0 mismatched, 0 insufficient permission, 0 missing from
> > publisher, 0 skipped, 5 no drift
> >
>
> Those are DEBUG1 messages, not LOG messages, so I think the primary
> goal is to ensure that they are full of useful information to help
> debugging.  Knowing the prior state information means we know that the
> "drift" logic was needed when deciding to sync or not.
>
> If message volume can be reduced without any loss of debugging
> usefulness, then great, but we need to take care not to throw the baby
> out with the bath water.
>
> If message volume is a problem, then maybe that should be addressed by
> using more log levels DEBUG1,DEBUG2,DEBUG3,... etc.
>

I am not totally against it, but I don=E2=80=99t find it particularly usefu=
l
to dump the state (INIT, READY), since we already log exactly which
sequences were updated individually (see below). The output below
covers both cases=E2=80=94sequences with drift and those in the INIT state.=
 We
also include the =E2=80=9Cno drift=E2=80=9D count. So all of these effectiv=
ely
summarizes the overall status.

logical replication sync for subscription "sub2", sequence
"public.myseq1" has been updated
logical replication sync for subscription "sub2", sequence
"public.myseq2" has been updated

 Even if we plan to retain multiple messages for INIT vs READY, I
guess, with copy_sequences() now suggested to be called only once
irrespective of 'state' will make it further tricky to separate out
these log messages for INIT and READY. But let's see.

> I think it is useful to discuss how much DEBUG information is
> required. However, I would like to know if this is related to the
> patch being discussed or a case in HEAD? If later, then it is better
> to discuss it separately and address it as a separate patch if
> required.

Amit, this is related to the new patch only.

thanks
Shveta