Improve pg_sync_replication_slots() to wait for primary to advance

Ajin Cherian <itsajin@gmail.com>

From: Ajin Cherian <itsajin@gmail.com>

To: PostgreSQL mailing lists <pgsql-hackers@postgresql.org>

Date: 2025-06-24T10:40:58Z

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 →

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

0001-Fix-stale-snapshot-issue.patch (application/octet-stream) patch 0001

Hello,

Creating this thread for a POC based on discussions in thread [1].
Hou-san had created this patch, and I just cleaned up some documents,
did some testing and now sharing the patch here.

In this patch, the pg_sync_replication_slots() API now waits
indefinitely for the remote slot to catch up. We could later add a
timeout parameter to control maximum wait time if this approach seems
acceptable. If there are more ideas on improving this patch, let me
know.

regards,
Ajin Cherian
[1]  - https://www.postgresql.org/message-id/CAF1DzPWTcg%2Bm%2Bx%2BoVVB%3Dy4q9%3DPYYsL_mujVp7uJr-_oUtWNGbA%40mail.gmail.com