Re: [HACKERS] More stats about skipped vacuums

Hello,

At Wed, 07 Feb 2018 16:59:20 -0500, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote in <3246(dot)1518040760(at)sss(dot)pgh(dot)pa(dot)us>
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> > It seems to me that there was a thread where Tom proposed removing
> > support for dynamic_shared_memory_type = none.
>
> I think you're recalling <32138(dot)1502675970(at)sss(dot)pgh(dot)pa(dot)us>, wherein
> I pointed out that
>
> >>> Whether that's worth the trouble is debatable. The current code
> >>> in initdb believes that every platform has some type of DSM support
> >>> (see choose_dsm_implementation). Nobody's complained about that,
> >>> and it certainly works on every buildfarm animal. So for all we know,
> >>> dynamic_shared_memory_type = none is broken already.
>
> (That was in fact in the same thread Kyotaro-san just linked to about
> reimplementing the stats collector.)
>
> It's still true that we've no reason to believe there are any supported
> platforms that haven't got some sort of DSM. Performance might be a
> different question, of course ... but it's hard to believe that
> transferring stats through DSM wouldn't be better than writing them
> out to files.

Good to hear. Thanks.

> > I suggest we remove support for dynamic_shared_memory_type = none first,
> > and see if we get any complaints. If we don't, then future patches can
> > rely on it being present.
>
> If we remove it in v11, it'd still be maybe a year from now before we'd
> have much confidence from that alone that nobody cares. I think the lack
> of complaints about it in 9.6 and 10 is a more useful data point.

So that means that we are assumed to be able to rely on the
existence of DSM at the present since over a year we had no
complain despite the fact that DSM is silently turned on? And
apart from that we are ready to remove 'none' from the options of
dynamic_shared_memory_type right now?

If I may rely on DSM, fallback stuff would not be required.

> regards, tom lane

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center