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

On Mon, Dec 13, 2021 at 11:05:46PM +0000, Bossart, Nathan wrote:
> On 12/13/21, 12:37 PM, "Robert Haas" <robertmhaas(at)gmail(dot)com> wrote:
> > On Mon, Dec 13, 2021 at 1:21 PM Bossart, Nathan <bossartn(at)amazon(dot)com> wrote:
> >> > But against all that, if these tasks are slowing down checkpoints and
> >> > that's avoidable, that seems pretty important too. Interestingly, I
> >> > can't say that I've ever seen any of these things be a problem for
> >> > checkpoint or startup speed. I wonder why you've had a different
> >> > experience.
> >>
> >> Yeah, it's difficult for me to justify why users should suffer long
> >> periods of downtime because startup or checkpointing is taking a very
> >> long time doing things that are arguably unrelated to startup and
> >> checkpointing.
> >
> > Well sure. But I've never actually seen that happen.
>
> I'll admit that surprises me. As noted elsewhere [0], we were seeing
> this enough with pgsql_tmp that we started moving the directory aside
> before starting the server. Discussions about handling this usually
> prompt questions about why there are so many temporary files in the
> first place (which is fair). FWIW all four functions noted in my
> original message [1] are things I've seen firsthand affecting users.

Have we changed temporary file handling in any recent major releases,
meaning is this a current problem or one already improved in PG 14.

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Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

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