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Message-ID: <37857474-5caa-ccb3-92a3-150ddfe851ab@enterprisedb.com>
Date: Wed, 14 Sep 2022 22:07:11 +0200
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Subject: Re: archive modules
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To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, =?UTF-8?Q?Benoit_Lobr=c3=a9au?=
 <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>,
 Michael Paquier <michael@paquier.xyz>, Magnus Hagander
 <magnus@hagander.net>, Stephen Frost <sfrost@snowman.net>
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From: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
In-Reply-To: <20220914200305.GA2984249@nathanxps13>
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On 14.09.22 22:03, Nathan Bossart wrote:
> On Wed, Sep 14, 2022 at 09:33:46PM +0200, Peter Eisentraut wrote:
>> Another question on this feature: Currently, if archive_library is set,
>> archive_command is ignored.  I think if both are set, it should be an error.
>> Compare for example what happens if you set multiple recovery_target_xxx
>> settings.  I don't think silently turning off one setting by setting another
>> is a good behavior.
> 
> I originally did it this way, but changed it based on this feedback [0].  I
> have no problem with the general idea, but the recovery_target_* logic does
> have the following note:
> 
> 	 * XXX this code is broken by design.  Throwing an error from a GUC assign
> 	 * hook breaks fundamental assumptions of guc.c.  So long as all the variables
> 	 * for which this can happen are PGC_POSTMASTER, the consequences are limited,
> 	 * since we'd just abort postmaster startup anyway.  Nonetheless it's likely
> 	 * that we have odd behaviors such as unexpected GUC ordering dependencies.

Ah yes, that won't work.  But maybe we can just check it at run time, 
like in LoadArchiveLibrary().