Re: recovery modules

From: Andres Freund <andres(at)anarazel(dot)de>
To: Nathan Bossart <nathandbossart(at)gmail(dot)com>
Cc: Michael Paquier <michael(at)paquier(dot)xyz>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: recovery modules
Date: 2023-01-28 00:09:39
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On 2023-01-27 15:28:21 -0800, Nathan Bossart wrote:
> The more I think about this, the more I wonder whether we really need to
> include archive_cleanup_command and recovery_end_command in recovery
> modules.

I think it would be hard to write a good module that isn't just implementing
the existing commands without it. Needing to clean up archives and reacting to
the end of recovery seems a pretty core task.

> Another weird thing with the checkpointer is that the restore_library will
> stay loaded long after recovery is finished, and it'll be loaded regardless
> of whether recovery is required in the first place.

I don't see a problem with that. And I suspect we might even end up there
for other reasons.

I was briefly wondering whether it'd be worth trying to offload things like
archive_cleanup_command from checkpointer to a different process, for
robustness. But given that it's pretty much required for performance that the
module runs in the startup process, that ship probably has sailed.


Andres Freund

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