Date: Fri, 14 Oct 2022 11:51:30 -0700
From: Nathan Bossart <nathandbossart@gmail.com>
To: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Tom Lane <tgl@sss.pgh.pa.us>,
	Peter Eisentraut <peter.eisentraut@enterprisedb.com>,
	Benoit =?iso-8859-1?Q?Lobr=E9au?= <benoit.lobreau@gmail.com>,
	Alvaro Herrera <alvherre@alvh.no-ip.org>,
	Robert Haas <robertmhaas@gmail.com>,
	"Bossart, Nathan" <bossartn@amazon.com>,
	David Steele <david@pgmasters.net>,
	Fujii Masao <masao.fujii@oss.nttdata.com>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>,
	Magnus Hagander <magnus@hagander.net>,
	Stephen Frost <sfrost@snowman.net>
Subject: Re: archive modules
Message-ID: <20221014185130.GC1678424@nathanxps13>
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On Fri, Oct 14, 2022 at 12:10:18PM +0530, Bharath Rupireddy wrote:
> +        ereport(ERROR,
> +                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
> +                 errmsg("both archive_command and archive_library specified"),
> +                 errdetail("Only one of archive_command,
> archive_library may be set.")));
> 
> The above errmsg looks informational. Can we just say something like
> below?  It doesn't require errdetail as the errmsg says it all. See
> the other instances elsewhere [2].
> 
>         ereport(ERROR,
>                 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
>                  errmsg("cannot specify both \"archive_command\" and
> \"archive_library\"")));

I modeled this after the ERROR that error_multiple_recovery_targets()
emits.  I don't think there's really any material difference between your
proposal and mine, but I don't have a strong opinion.

> 2) I think we have a problem - set archive_mode and archive_library
> and start the server, then set archive_command, reload the conf, see
> [3] - the archiver needs to error out right? The archiver gets
> restarted whenever archive_library changes but not when
> archive_command changes. I think the right place for the error is
> after or at the end of HandlePgArchInterrupts().

Good catch.  You are right, this is broken.  I believe that we need to
check for the misconfiguration in HandlePgArchInterrupts() in addition to
LoadArchiveLibrary().  I will work on fixing this.

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