Re: Should we increase the default vacuum_cost_limit?

On Sat, 9 Mar 2019 at 07:10, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> Jeff Janes <jeff(dot)janes(at)gmail(dot)com> writes:
> > Now that this is done, the default value is only 5x below the hard-coded
> > maximum of 10,000.
> > This seems a bit odd, and not very future-proof. Especially since the
> > hard-coded maximum appears to have no logic to it anyway, at least none
> > that is documented. Is it just mindless nannyism?
>
> Hm. I think the idea was that rather than setting it to "something very
> large", you'd want to just disable the feature via vacuum_cost_delay.
> But I agree that the threshold for what is ridiculously large probably
> ought to be well more than 5x the default, and maybe it is just mindless
> nannyism to have a limit less than what the implementation can handle.

Yeah, +1 to increasing it. I imagine that the 10,000 limit would not
allow people to explore the upper limits of a modern PCI-E SSD with
the standard delay time and dirty/miss scores. Also, it doesn't seem
entirely unreasonable that someone somewhere might also want to
fine-tune the hit/miss/dirty scores so that they're some larger factor
apart from each other the standard scores are. The 10,000 limit does
not allow much wiggle room for that.

--
David Rowley http://www.2ndQuadrant.com/
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