Re: archive wal's failure and load increase.

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От Tom Lane
Тема Re: archive wal's failure and load increase.
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Msg-id 15270.1159540162@sss.pgh.pa.us
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Ответ на Re: archive wal's failure and load increase.  (Simon Riggs <simon@2ndquadrant.com>)
Ответы Re: archive wal's failure and load increase.  (Simon Riggs <simon@2ndquadrant.com>)
Список pgsql-performance
Simon Riggs <simon@2ndquadrant.com> writes:
> We discussed putting PreallocXlogFiles() in bgwriter once before, but I
> think last time we discussed that idea it was rejected, IIRC.

We already do that: it's called a checkpoint.  If the rate of WAL
generation was more than checkpoint_segments per checkpoint_timeout,
then indeed there would be a problem with foreground processes having to
manufacture WAL segment files for themselves, but it would be a bursty
thing (ie, problem goes away after a checkpoint, then comes back).

It's a good thought but I don't think the theory holds water for
explaining Cedric's problem, unless there was *also* some effect
preventing checkpoints from completing ... which would be a much more
serious problem than the archiver failing.

            regards, tom lane

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