Subject: Startup process stuck on WAL replay

From: Nikhil Shetty <[email-masked]>
Date: Tue, 4 Nov 2025 22:12:38 +0530

Hi All,

The startup process on a replica is stuck on a WAL for a long time
LSN - F46/FB4FCF88

We verified this from pg_stat_replication output

We did a WAL dump to see the xact for this LSN and it shows as below

rmgr: Heap2       len (rec/tot):     56/    56, tx:          0, lsn:
F46/FB4FCF88, prev F46/FB4FCF40, desc: PRUNE latestRemovedXid 884637333
nredirected 0 ndead 1, blkref #0: rel 1663/16402/72663 blk 0
Would such a xact cause WAL replay to get stuck ? Or is it some other
issue? Is there any way to check where it is stuck , strace was not helpful

Thanks,
Nikhil

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From: Fabrice Chapuis <[email-masked]>
Date: Wed, 5 Nov 2025 10:19:50 +0100

Hi Nikhil,

Did you try to use this query to see if kind of wait event exists?

SELECT pid, usename, wait_event_type, wait_event, query
FROM pg_stat_activity
WHERE backend_type = 'startup';

Regards,

Fabrice