Re: Slot's restart_lsn may point to removed WAL segment after hard restart unexpectedly

Alexander Lakhin <exclusion@gmail.com>

From: Alexander Lakhin <exclusion@gmail.com>

To: Alexander Korotkov <aekorotkov@gmail.com>

Cc: Vitaly Davydov <v.davydov@postgrespro.ru>, Amit Kapila <amit.kapila16@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Masahiko Sawada <sawada.mshk@gmail.com>, tomas@vondra.me

Date: 2025-06-15T15:00:01Z

Lists: pgsql-hackers

Commits

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Update comment for ReplicationSlot.last_saved_restart_lsn
- 0810fbb02dbe 19 (unreleased) landed
Fix CheckPointReplicationSlots() with max_replication_slots == 0
- 7195c804bd12 18.0 landed
Remove excess assert from InvalidatePossiblyObsoleteSlot()
- 70d8a91f82f1 18.0 landed
Improve runtime and output of tests for replication slots checkpointing.
- 5ed50f9386f0 17.6 landed
- 4464fddf7b50 18.0 landed
Keep WAL segments by slot's last saved restart LSN
- ca307d5cec90 18.0 landed
Fix an assert in CheckPointReplicationSlots().
- d1ffcc7fa3c5 17.0 cited

15.06.2025 14:02, Alexander Korotkov wrote:
> Could you, please, check this patch?  On my system it makes 046 and
> 047 execute in 140 secs with -O0 and -DRELCACHE_FORCE_RELEASE
> -DCATCACHE_FORCE_RELEASE.

Thank you for the patch!

It decreases the test's duration significantly:
# +++ tap check in src/test/recovery +++
t/046_checkpoint_logical_slot.pl .. ok
All tests successful.
Files=1, Tests=1, 29 wallclock secs ( 0.01 usr  0.00 sys +  0.23 cusr  0.56 csys =  0.80 CPU)

Without the patch:
t/046_checkpoint_logical_slot.pl .. ok
All tests successful.
Files=1, Tests=1, 519 wallclock secs ( 0.01 usr  0.00 sys +  3.05 cusr  7.64 csys = 10.70 CPU)
Result: PASS

Best regards,
Alexander