Re: O(n) tasks cause lengthy startups and checkpoints

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От Nathan Bossart
Тема Re: O(n) tasks cause lengthy startups and checkpoints
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Msg-id 20220218164454.GA3403811@nathanxps13
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Ответ на Re: O(n) tasks cause lengthy startups and checkpoints  (Andres Freund <andres@anarazel.de>)
Ответы Re: O(n) tasks cause lengthy startups and checkpoints
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On Thu, Feb 17, 2022 at 03:12:47PM -0800, Andres Freund wrote:
>> > The improvements around deleting temporary files and serialized snapshots
>> > afaict don't require a dedicated process - they're only relevant during
>> > startup. We could use the approach of renaming the directory out of the way as
>> > done in this patchset but perform the cleanup in the startup process after
>> > we're up.
>> 
>> Perhaps this is a good place to start.  As I mentioned above, IME the
>> temporary file cleanup is the most common problem, so I think even getting
>> that one fixed would be a huge improvement.
> 
> Cool.

Hm.  How should this work for standbys?  I can think of the following
options:
    1. Do temporary file cleanup in the postmaster (as it does today).
    2. Pause after allowing connections to clean up temporary files.
    3. Do small amounts of temporary file cleanup whenever there is an
       opportunity during recovery.
    4. Wait until recovery completes before cleaning up temporary files.

I'm not too thrilled about any of these options.

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



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