Re: RFE: Make statistics robust for unplanned events

>
>
> Yeah, that's what I was thinking as well -- dumping snapshot at
> regular intervals, so that on crash recovery we lose a "controlled
> amount" of recent starts instead of losing *everything*.
>
> I think in most situations a fairly long interval is OK -- if you have
> tables that take so many hits that you need a really quick reaction
> from autovacuum it will probably pick that up quickly enough even
> after a reset. And if it's moer the long-term tracking that's
> important, then a longer interval is probably OK.
>
> But perhaps make it configurable with a timeout and a "reasonable default"?
>
>
> > Patrik, for your use cases, would loosing at most the stats since the
> > start of last checkpoint be an issue?
>
> Unless there's a particular benefit to tie it specifically to the
> checkpoint occuring, I'd rather keep it as a separate setting. They
> might both come with the same default of course, btu I can certainly
> envision cases where you want to increase the checkpoint distance
> while keeping the stats interval lower for example. Many people
> increase the checkpoint timeout quite a lot...
>
>
From what I understand, I think it depends on the interval of those
checkpoints. If the interval was configurable with the mentioned reasonable
default, then it shouldn't be an issue.

If we were to choose a hard coded interval of those checkpoints based on my
case, I would have to consult the original reporter, but then it might not
suit others anyway. Therefore, making it configurable makes more sense to
me personally.

--
Patrik Novotný
Associate Software Engineer
Red Hat
panovotn(at)redhat(dot)com