Date: Wed, 3 Aug 2022 00:16:17 -0700
From: Noah Misch <noah@leadboat.com>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: David Steele <david@pgmasters.net>,
	Kyotaro Horiguchi <horikyota.ntt@gmail.com>, robertmhaas@gmail.com,
	masao.fujii@oss.nttdata.com, pgsql-hackers@postgresql.org
Subject: Re: remove more archiving overhead
Message-ID: <20220803071617.GA3817792@rfd.leadboat.com>
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On Mon, Aug 01, 2022 at 10:02:19PM -0700, Nathan Bossart wrote:
> On Sat, Jul 30, 2022 at 11:51:56PM -0700, Noah Misch wrote:
> > Inviting the administrator to resolve things is more dangerous than just
> > returning true.  I recommend making this text more opinionated and simpler:
> > libraries must return true.  Alternately, if some library has found a good
> > reason to return false, this paragraph could give the reason.  I don't know of
> > such a reason, though.
> 
> Your suggestion seems reasonable to me.  I've attached a small patch.

> --- a/doc/src/sgml/backup.sgml
> +++ b/doc/src/sgml/backup.sgml
> @@ -691,11 +691,9 @@ test ! -f /mnt/server/archivedir/00000001000000A900000065 &amp;&amp; cp pg_wal/0
>      system crashes before the server makes a durable record of archival success,
>      the server will attempt to archive the file again after restarting (provided
>      archiving is still enabled).  When an archive library encounters a
> -    pre-existing file, it may return <literal>true</literal> if the WAL file has
> +    pre-existing file, it should return <literal>true</literal> if the WAL file has
>      identical contents to the pre-existing archive and the pre-existing archive
> -    is fully persisted to storage.  Alternatively, the archive library may
> -    return <literal>false</literal> anytime a pre-existing file is encountered,
> -    but this will require manual action by an administrator to resolve.  If a
> +    is fully persisted to storage.  If a
>      pre-existing file contains different contents than the WAL file being
>      archived, the archive library <emphasis>must</emphasis> return
>      <literal>false</literal>.

Works for me.  Thanks.