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

Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>

From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>

To: Amit Kapila <amit.kapila16@gmail.com>

Cc: Ashutosh Sharma <ashu.coek88@gmail.com>, Ajin Cherian <itsajin@gmail.com>, shveta malik <shveta.malik@gmail.com>, PostgreSQL mailing lists <pgsql-hackers@postgresql.org>

Date: 2025-09-08T04:21:23Z

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

On Sat, Sep 6, 2025 at 9:14 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Fri, Sep 5, 2025 at 11:39 PM Ashutosh Sharma <ashu.coek88@gmail.com> wrote:
> > If the remote slot is inactive since long and lagging behind the
> > standby, this function (pg_sync_replication_slots) could end up
> > waiting indefinitely. While it can certainly be cancelled manually,
> > that behavior might not be ideal for everyone. That’s my
> > understanding; please let me know if you see it differently.
> >
>
> Such a case can be addressed by having additional timeout parameters.
> We can do that as an additional patch if the use case is important
> enough to address.
>

Or we could rely on statement_timeout or the user cancelling the query
explicitly.

-- 
Best Wishes,
Ashutosh Bapat