From 70d8a91f82f19d270facd25bb6292a949773dfce Mon Sep 17 00:00:00 2001 From: Alexander Korotkov <akorotkov@postgresql.org> Date: Mon, 23 Jun 2025 21:27:42 +0300 Subject: [PATCH] Remove excess assert from InvalidatePossiblyObsoleteSlot() ca307d5cec90 introduced keeping WAL segments by slot's last saved restart LSN. It also added an assertion that the slot's restart LSN never goes backward. However, situations when the restart LSN goes backward have been spotted by buildfarm animals and investigated in the thread. When pg_receivewal starts the replication, it sets the last replayed LSN to the beginning of the segment, which is older than what ReplicationSlotReserveWal() set for the slot. A similar situation can happen to pg_basebackup. When standby reconnects to the primary, it sends the last replayed LSN, which might be older than the last confirmed flush LSN. In both these situations, a concurrent checkpoint may trigger an assert trap. Based on ideas from Vitaly Davydov <v.davydov@postgrespro.ru>, Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>, Vignesh C <vignesh21@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>. Reported-by: Vignesh C <vignesh21@gmail.com> Reported-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/CALDaNm3s-jpQTe1MshsvQ8GO%3DTLj233JCdkQ7uZ6pwqRVpxAdw%40mail.gmail.com Reviewed-by: Vignesh C <vignesh21@gmail.com> Reviewed-by: Amit Kapila <amit.kapila16@gmail.com> --- src/backend/replication/slot.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c index c64f020742f..c11e588d632 100644 --- a/src/backend/replication/slot.c +++ b/src/backend/replication/slot.c @@ -1810,8 +1810,6 @@ InvalidatePossiblyObsoleteSlot(uint32 possible_causes, */ SpinLockAcquire(&s->mutex); - Assert(s->data.restart_lsn >= s->last_saved_restart_lsn); - restart_lsn = s->data.restart_lsn; /* we do nothing if the slot is already invalid */