Date: Sat, 5 Nov 2022 14:08:58 -0700
From: Nathan Bossart <nathandbossart@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
	bharath.rupireddyforpostgres@gmail.com, tgl@sss.pgh.pa.us,
	peter.eisentraut@enterprisedb.com, benoit.lobreau@gmail.com,
	alvherre@alvh.no-ip.org, robertmhaas@gmail.com, bossartn@amazon.com,
	david@pgmasters.net, masao.fujii@oss.nttdata.com,
	pgsql-hackers@postgresql.org, magnus@hagander.net,
	sfrost@snowman.net
Subject: Re: archive modules
Message-ID: <20221105210858.GB137360@nathanxps13>
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On Mon, Oct 17, 2022 at 02:49:51PM +0900, Michael Paquier wrote:
> And, by the way, this patch would prevent the existence of archive
> modules that need to be loaded but *want* an archive_command with
> what they want to achieve.  That does not strike me as a good idea if
> we want to have a maximum of flexibility with this facility.

Such a module could define a custom GUC that accepts a shell command.  I
don't think we should overload the meaning of archive_command based on the
whims of whatever archive module is loaded.  Besides the potential end-user
confusion, your archive_command might be unexpectedly used incorrectly if
you forget to set archive_library.

Perhaps we could eventually move the archive_command functionality to a
contrib module (i.e., "shell_archive") so that users must always set
archive_library.  But until then, I suspect it's better to treat modules
and commands as two separate interfaces to ease migration from older major
versions (even though archive_command is now essentially a built-in archive
module).

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