Re: Startup PANIC on standby promotion due to zero-filled WAL segment

Alena Vinter <dlaaren8@gmail.com>

From: Alena Vinter <dlaaren8@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-12-25T08:47:05Z
Lists: pgsql-hackers

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I like the idea of preventing promotion to avoid such failures -- it sounds
reasonable.

However, we still have the problem: if the standby is stopped with
non-replicated TLI 2, it will fail to start:
"FATAL: according to history file, WAL location Y belongs to timeline X,
but previous recovered WAL file came from timeline X+1".
This happens even if no promotion is attempted — just a plain restart of
the standby. So the issue isn’t only about when to allow promotion.

Regarding my proposed solution: could you clarify why it isn’t correct? I’d
appreciate more detail so I can address your concerns.

---
Alena Vinter