Re: asynchronous execution

At Thu, 31 Aug 2017 21:52:36 +0900 (Tokyo Standard Time), Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote in <20170831(dot)215236(dot)135328985(dot)horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>
> At Thu, 03 Aug 2017 09:30:57 +0900 (Tokyo Standard Time), Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote in <20170803(dot)093057(dot)261590619(dot)horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>
> > > Unfortunately, that's probably another gigantic patch (that
> > > should probably be written by Andres).
> >
> > Yeah, but async executor on the current style of executor seems
> > furtile work, or sitting until the patch comes is also waste of
> > time. So I'm planning to include the following sutff in the next
> > PoC patch. Even I'm not sure it can land on the coming
> > Andres'patch.
> >
> > - Tuple passing outside call-stack. (I remember it was in the
> > past of the thread around but not found)
> >
> > This should be included in the Andres' patch.
> >
> > - Give executor an ability to run from data-source (or driver)
> > nodes to the root.
> >
> > I'm not sure this is included, but I suppose he is aiming this
> > kind of thing.
> >
> > - Rebuid asynchronous execution on the upside-down executor.
>
> Anyway, I modified ExecProcNode into push-up form and it *seems*
> working to some extent. But trigger and cursors are almost broken
> and several other regressions fail. Some nodes such like
> windowagg are terriblly difficult to change to this push-up form
> (using state machine). And of course it is terribly inefficient.
>
> I'm afraid that all of this turns out to be in vain. But anyway,
> and FWIW, I'll show the work to here after some cleansing work on
> it.

So, this is that. Maybe this is really a bad way to go. Top of
the bads is it's terriblly hard to maintain because the behavior
of the state machine constructed in this patch is hardly
predictable so easily broken. During the 'cleansing work' I had
many crash or infinite-loop and they were a bit hard to
diagnose.. This will be soon broken by following commits.

Anyway and, again FWIW, this is that. I'll leave this for a while
(at least the period of this CF) and reconsider on async in
different forms.

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center