Date: Mon, 11 Apr 2022 09:52:57 -0700
From: Nathan Bossart <nathandbossart@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>,
	Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: avoid multiple hard links to same WAL file after a crash
Message-ID: <20220411165257.GB1915258@nathanxps13>
References: <20220407182954.GA1231544@nathanxps13>
 <20220411.181217.1988132552983948196.horikyota.ntt@gmail.com>
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 <289699.1649694527@sss.pgh.pa.us>
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On Mon, Apr 11, 2022 at 12:28:47PM -0400, Tom Lane wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> On Mon, Apr 11, 2022 at 5:12 AM Kyotaro Horiguchi
>> <horikyota.ntt@gmail.com> wrote:
>>> If this diagnosis is correct, the comment is proved to be paranoid.
> 
>> It's sometimes difficult to understand what problems really old code
>> comments are worrying about. For example, could they have been
>> worrying about bugs in the code? Could they have been worrying about
>> manual interference with the pg_wal directory? It's hard to know.
> 
> "git blame" can be helpful here, if you trace back to when the comment
> was written and then try to find the associated mailing-list discussion.
> (That leap can be difficult for commits pre-dating our current
> convention of including links in the commit message, but it's usually
> not *that* hard to locate contemporaneous discussion.)

I traced this back a while ago.  I believe the link() was first added in
November 2000 as part of f0e37a8.  This even predates WAL recycling, which
was added in July 2001 as part of 7d4d5c0.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com