Horton

Re: archive modules

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Cc: Nathan Bossart <nathandbossart@gmail.com>, Benoit Lobréau <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>
Date: 2022-09-14T20:47:23Z
Lists: pgsql-hackers 
Peter Eisentraut <peter.eisentraut@enterprisedb.com> writes:
> On 14.09.22 22:03, Nathan Bossart wrote:
>> 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().

Yeah, the objection there is only to trying to enforce such
interrelationships in GUC hooks.  In this case it seems to me that
we could easily check and complain at the point where we're about
to use the GUC values.

			regards, tom lane

Commits

  1. Disallow setting archive_library and archive_command at the same time

  2. Restore archive_command documentation

  3. Doc: improve explanation of when custom GUCs appear in pg_settings.

  4. doc: Add note about re-archiving of same WAL files in docs.

  5. In basic_archive tests, insist on wal_level='replica'.

  6. Allow archiving via loadable modules.

  7. Move the code to archive files via the shell to a separate file.