Re: Improve pg_sync_replication_slots() to wait for primary to advance

Ajin Cherian <itsajin@gmail.com>

From: Ajin Cherian <itsajin@gmail.com>

To: shveta malik <shveta.malik@gmail.com>

Cc: Ashutosh Sharma <ashu.coek88@gmail.com>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, PostgreSQL mailing lists <pgsql-hackers@postgresql.org>

Date: 2025-10-02T11:23:34Z

Lists: pgsql-hackers

Commits

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Enhance slot synchronization API to respect promotion signal.
- 4bed04d39566 17.10 landed
- 94efd308bcec 18.4 landed
- 1362bc33e025 19 (unreleased) landed
Fix inconsistent elevel in pg_sync_replication_slots() retry logic.
- f1ddaa15357f 19 (unreleased) landed
Refactor slot synchronization logic in slotsync.c.
- 788ec96d591d 19 (unreleased) landed
Fix intermittent BF failure in 040_standby_failover_slots_sync.
- b47c50e5667b 19 (unreleased) landed
Add retry logic to pg_sync_replication_slots().
- 0d2d4a0ec3ec 19 (unreleased) landed
Fix LOCK_TIMEOUT handling in slotsync worker.
- 04396eacd3fa 19 (unreleased) cited
Add slotsync skip statistics.
- 76b78721ca49 19 (unreleased) cited

Attachments

v15-0001-Improve-initial-slot-synchronization-in-pg_sync_.patch (application/octet-stream) patch v15-0001

On Fri, Sep 26, 2025 at 8:14 PM shveta malik <shveta.malik@gmail.com> wrote:
>
>
> It seems it is missed to be changed perhaps due to bringing back
> previous implementation of slotsync_api_reread_config()
>
> >
> > > b)
> > > There is double space in DETAIL msg: "have changed  since"
> > >
> > > Will it be better to shorten the DETAIL as: 'One or more of
> > > primary_conninfo, primary_slot_name, or hot_standby_feedback were
> > > modified.'
> > >
> >
> > Changed.
> >

Fixed.

>
> This too is missed.
>
> > > 6)
> > > postgres=# SELECT pg_sync_replication_slots();
> > > ERROR:  exiting from slot synchronization as promotion is triggered
> > >
> > > Shall we rephrase it similar to the previous message: 'cannot continue
> > > replication slots synchronization as standby promotion is triggered'
> > >
> > Changed.
> >
> > Attaching patch v14 incorporating the above changes.
> >
>

This was rephrased.

> Few trivial comments:
>
> 1)
> slotsync_api_reread_config():
> + * Returns true if conninfo, primary_slot_name or hot_standby_feedback changed.
>
> This comment is no longer valid, we can remove it.
>

Removed.

> 2)
>   /* We are done with sync, so reset sync flag */
>   reset_syncing_flag();
> +
>
> This extra blank line is not needed.

Fixed.

Attaching patch v15 addressing these comments.

regards,
Ajin Cherian
Fujitsu Australia