Horton

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

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: shveta malik <shveta.malik@gmail.com>
Cc: Ajin Cherian <itsajin@gmail.com>, PostgreSQL mailing lists <pgsql-hackers@postgresql.org>
Date: 2025-08-05T06:22:39Z
Lists: pgsql-hackers

Commits

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  1. Enhance slot synchronization API to respect promotion signal.

  2. Fix inconsistent elevel in pg_sync_replication_slots() retry logic.

  3. Refactor slot synchronization logic in slotsync.c.

  4. Fix intermittent BF failure in 040_standby_failover_slots_sync.

  5. Add retry logic to pg_sync_replication_slots().

  6. Fix LOCK_TIMEOUT handling in slotsync worker.

  7. Add slotsync skip statistics.

On Tue, Aug 5, 2025 at 9:28 AM shveta malik <shveta.malik@gmail.com> wrote:
>
> On Mon, Aug 4, 2025 at 3:41 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Mon, Aug 4, 2025 at 12:19 PM shveta malik <shveta.malik@gmail.com> wrote:
>
> If we want to avoid continuously syncing newly added slots in later
> cycles and instead focus only on the ones that failed to sync during
> the first attempt, one approach is to maintain a list of failed slots
> from the initial cycle and only retry those in subsequent attempts.
> But this will add complexity to the implementation.
>

There will be some additional code for this but overall it improves
the code in the lower level functions. We may want to use the existing
remote_slot list for this purpose.

The current proposed change in low-level functions appears to be
difficult to maintain, especially the change proposed in
update_and_persist_local_synced_slot(). If we can find a better way to
achieve the same then we can consider the current approach as well.

-- 
With Regards,
Amit Kapila.