Subject: Re: Make mesage at end-of-recovery less scary.
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>, andres@anarazel.de
References: <20200305.160650.1027844943773682801.horikyota.ntt@gmail.com>
 <4a9fc5b1-34c8-46ec-9b71-d4763d70311d@2ndquadrant.com>
 <20200323194736.uijmupfle2ccvyah@alap3.anarazel.de>
 <20200324.105250.1584846618506385212.horikyota.ntt@gmail.com>
Cc: michael@paquier.xyz, pgsql-hackers@lists.postgresql.org
From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Organization: 2ndQuadrant
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Date: Wed, 25 Mar 2020 13:53:23 +0100
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On 2020-03-24 02:52, Kyotaro Horiguchi wrote:
>> I don't find that very satisfying, but I can't come up with something
>> that provides the current information, while being less scary than my
>> suggestion?
> The 0-length record is not an "invalid" state during recovery, so we
> can add the message for the state as "record length is 0 at %X/%X". I
> think if other states found there, it implies something wrong.
> 
> LSN is redundantly shown but I'm not sure if it is better to remove it
> from either of the two lines.
> 
> | LOG:  reached end of WAL at 0/3000850 on timeline 1 in pg_wal during crash recovery
> | DETAIL:  record length is 0 at 0/3000850

I'm not up to date on all these details, but my high-level idea would be 
some kind of hint associated with the existing error messages, like:

HINT:  This is to be expected if this is the end of the WAL.  Otherwise, 
it could indicate corruption.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services