Horton

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

shveta malik <shveta.malik@gmail.com>

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From: shveta malik <shveta.malik@gmail.com>
To: Ajin Cherian <itsajin@gmail.com>
Cc: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Japin Li <japinli@hotmail.com>, Ashutosh Sharma <ashu.coek88@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, PostgreSQL mailing lists <pgsql-hackers@postgresql.org>, shveta malik <shveta.malik@gmail.com>
Date: 2025-11-28T06:25:18Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  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 Fri, Nov 28, 2025 at 10:16 AM Ajin Cherian <itsajin@gmail.com> wrote:
>
>
> Fixed as above.
>
> I've addressed the above comments as well as rebased the patch based
> on changes in commit 76b7872 in patch v26
>

Thanks for the patch. Please find a few trivial comments:

1)
+ if (AmLogicalSlotSyncWorkerProcess())
+ Assert(sync_replication_slots);

Here too we can use 'worker'.

2)
+ /* check for sync_replication_slots change */

check --> Check

3)
Assert (!worker)
Extra space in between.

4)
check_and_set_sync_info() and ShutDownSlotSync() refers to the pid as
worker_pid. But now it could be backend-pid as well.
Using 'worker' in this variable could be misleading. Shall we make it
sync_process_pid?

5)
/*
 * Interrupt handler for main loop of slot sync worker.
 */
static void
ProcessSlotSyncInterrupts()

We can modify the comment to include API as well.

6)
/*
 * Shut down the slot sync worker.
 *
 * This function sends signal to shutdown slot sync worker, if required. It
 * also waits till the slot sync worker has exited or
 * pg_sync_replication_slots() has finished.
 */
void
ShutDownSlotSync(void)

We should change comments to give details on API as well.

7)
+# Remove the standby from the synchronized_standby_slots list and reload the
+# configuration.
+$primary->adjust_conf('postgresql.conf', 'synchronized_standby_slots', "''");
+$primary->reload;

We can update the comment to below for better clarity:
Remove the dropped sb1_slot from the ...

8)
+# Attempt to synchronize slots using API. The API will continue retrying
+# synchronization until the remote slot catches up.
+# The API will not return until this happens, to be able to make
+# further calls, call the API in a background process.

We can move these comments atop:
my $h = $standby2->background_psql('postgres', on_error_stop => 0);

thanks
Shveta