Horton

archive modules

Nathan Bossart <bossartn@amazon.com>

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From: "Bossart, Nathan" <bossartn@amazon.com>
To: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2021-11-01T18:54:51Z
Lists: pgsql-hackers

Attachments

This thread is a continuation of the thread with the subject
"parallelizing the archiver" [0].  That thread had morphed into an
effort to allow creating archive modules, so I've created a new one to
ensure that this topic has the proper visibility.

I've attached the latest patch from the previous thread.  This patch
does a few things.  First, it adds the archive_library GUC that
specifies a library to use in place of archive_command.  If
archive_library is set to "shell" (the default), archive_command is
still used.  The archive_library is preloaded, so its _PG_init() can
do anything that libraries loaded via shared_preload_libraries can do.
Like logical decoding output plugins, archive modules must define an
initialization function and some callbacks.  The patch also introduces
the basic_archive module to ensure test coverage on the new
infrastructure.

Nathan

[0] https://www.postgresql.org/message-id/flat/BC4D6BB2-6976-4397-A417-A6A30EEDC63E%40amazon.com

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.