Date: Tue, 14 Dec 2021 13:04:56 +0900 (JST)
Message-Id: <20211214.130456.2233153190058148084.horikyota.ntt@gmail.com>
To: pgsql-hackers@postgresql.org
Subject: more descriptive message for process termination due to
 max_slot_wal_keep_size
From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
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Hello.

As complained in pgsql-bugs [1], when a process is terminated due to
max_slot_wal_keep_size, the related messages don't mention the root
cause for *the termination*.  Note that the third message does not
show for temporary replication slots.

[pid=a] LOG:  terminating process x to release replication slot "s"
[pid=x] LOG:  FATAL:  terminating connection due to administrator command
[pid=a] LOG:  invalidting slot "s" because its restart_lsn X/X exceeds max_slot_wal_keep_size

The attached patch attaches a DETAIL line to the first message.

> [17605] LOG:  terminating process 17614 to release replication slot "s1"
+ [17605] DETAIL:  The slot's restart_lsn 0/2C0000A0 exceeds max_slot_wal_keep_size.
> [17614] FATAL:  terminating connection due to administrator command
> [17605] LOG:  invalidating slot "s1" because its restart_lsn 0/2C0000A0 exceeds max_slot_wal_keep_size

Somewhat the second and fourth lines look inconsistent each other but
that wouldn't be such a problem.  I don't think we want to concatenate
the two lines together as the result is a bit too long.

> LOG:  terminating process 17614 to release replication slot "s1" because it's restart_lsn 0/2C0000A0 exceeds max_slot_wal_keep_size.

What do you think about this?

[1] https://www.postgresql.org/message-id/20211214.101137.379073733372253470.horikyota.ntt%40gmail.com

-- 
Kyotaro Horiguchi
NTT Open Source Software Center

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