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From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Fri, 24 Dec 2021 17:37:51 +0530
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 <CALj2ACWpaOnZrg5FT+bm19WAqBgvgj_coAMikrSMEpQofThjRA@mail.gmail.com>
Subject: Re: Add checkpoint and redo LSN to LogCheckpointEnd log message
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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On Fri, Dec 24, 2021 at 11:21 AM Kyotaro Horiguchi
<horikyota.ntt@gmail.com> wrote:
>
> 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.

Thanks for the review. I've added a CF entry to not lose track -
https://commitfest.postgresql.org/36/3474/.

> > [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]

Yeah the proposed in the v1 is clear saying checkpoint/restartpoint
LSN and REDO LSN.

Regards,
Bharath Rupireddy.