Re: [HACKERS] asynchronous execution - Mailing list pgsql-hackers

From Kyotaro HORIGUCHI
Subject Re: [HACKERS] asynchronous execution
Date
Msg-id 20170728.173129.214754483.horiguchi.kyotaro@lab.ntt.co.jp
Whole thread Raw
In response to Re: [HACKERS] asynchronous execution  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
Thank you for the comment.

At Wed, 26 Jul 2017 17:16:43 -0400, Robert Haas <robertmhaas@gmail.com> wrote in
<CA+TgmoYrbgTBnLwnr1v=pk+C=znWg7AgV9=M9ehrq6TDexPQNw@mail.gmail.com>
> But if we do, then I fear we'll just be reintroducing the same
> performance regression that we introduced by switching to this
> framework from the previous one - or maybe a different one, but a
> regression all the same.  Every type of intermediate node will have to
> have a code path where it uses ExecAsyncRequest() /
> ExecAyncHogeResponse() rather than ExecProcNode() to get tuples, and

I understand what Robert concerns and I think I share the same
opinion. It needs further different framework.

At Thu, 27 Jul 2017 06:39:51 -0400, Robert Haas <robertmhaas@gmail.com> wrote in
<CA+Tgmoa=ke_zfucOAa3YEUnBSC=FSXn8SU2aYc8PGBBp=Yy9fw@mail.gmail.com>
> On Wed, Jul 26, 2017 at 5:43 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > I have not been paying any attention to this thread whatsoever,
> > but I wonder if you can address your problem by building on top of
> > the ExecProcNode replacement that Andres is working on,
> > https://www.postgresql.org/message-id/20170726012641.bmhfcp5ajpudihl6@alap3.anarazel.de
> >
> > The scheme he has allows $extra_stuff to be injected into ExecProcNode at
> > no cost when $extra_stuff is not needed, because you simply don't insert
> > the wrapper function when it's not needed.  I'm not sure that it will
> > scale well to several different kinds of insertions though, for instance
> > if you wanted both instrumentation and async support on the same node.
> > But maybe those two couldn't be arms-length from each other anyway,
> > in which case it might be fine as-is.
> 
> Yeah, I don't quite see how that would apply in this case -- what we
> need here is not as simple as just conditionally injecting an extra
> bit.

Thank you for the pointer, Tom. The subject (segfault in HEAD...)
haven't made me think that this kind of discussion was held
there. Anyway it seems very closer to asynchronous execution so
I'll catch up it considering how I can associate with this.

Regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center




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