Date: Fri, 24 Dec 2021 14:51:34 +0900 (JST)
Message-Id: <20211224.145134.1164706994861031206.horikyota.ntt@gmail.com>
To: bharath.rupireddyforpostgres@gmail.com
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Add checkpoint and redo LSN to LogCheckpointEnd log message
From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
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At Thu, 23 Dec 2021 20:35:54 +0530, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> wrote in 
> Hi,
> 
> It is useful (for debugging purposes) if the checkpoint end message
> has the checkpoint LSN and REDO LSN [1]. It gives more context while
> analyzing checkpoint-related issues. The pg_controldata gives the last
> checkpoint LSN and REDO LSN, but having this info alongside the log
> message helps analyze issues that happened previously, connect the
> dots and identify the root cause.
> 
> Attaching a small patch herewith. Thoughts?

A big +1 from me.  I thought about proposing the same in the past.

> [1]
> 2021-12-23 14:58:54.694 UTC [1965649] LOG:  checkpoint starting:
> shutdown immediate
> 2021-12-23 14:58:54.714 UTC [1965649] LOG:  checkpoint complete: wrote
> 0 buffers (0.0%); 0 WAL file(s) added, 0 removed, 0 recycled;
> write=0.001 s, sync=0.001 s, total=0.025 s; sync files=0,
> longest=0.000 s, average=0.000 s; distance=0 kB, estimate=0 kB;
> LSN=0/14D0AD0, REDO LSN=0/14D0AD0

I thougt about something like the following, but your proposal may be
clearer.

> WAL range=[0/14D0340, 0/14D0AD0]

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center