At Wed, 07 Feb 2018 16:59:20 -0500, Tom Lane <t...@sss.pgh.pa.us> wrote in 
> Robert Haas <robertmh...@gmail.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 <32138.1502675...@sss.pgh.pa.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


Kyotaro Horiguchi
NTT Open Source Software Center

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