Re: max_parallel_degree > 0 for 9.6 beta

On Thu, Aug 4, 2016 at 9:25 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Thu, Aug 4, 2016 at 12:56 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > Noah Misch <noah(at)leadboat(dot)com> writes:
> >> On Wed, Apr 20, 2016 at 02:28:15PM -0400, Tom Lane wrote:
> >>> +1, but let's put an entry on the 9.6 open-items page to remind us to
> >>> make that decision at the right time.
> >
> >> It's that time. Do we restore the max_parallel_workers_per_gather=0
> default,
> >> or is enabling this by default the right thing after all?
> >
> > At this point I'd have to vote against enabling by default in 9.6. The
> > fact that in the past week we've found bugs as bad as e1a93dd6a does not
> > give me a warm fuzzy feeling about the parallel-query code being ready
> > for prime time.
> >
> > Of course the question is how do we ever get to that point if we chicken
> > out with enabling it by default now. Maybe we could keep it turned on
> > in HEAD.
>
> However, we have a long track
> record of being cautious about things like this, so I would be OK with
> the idea of disabling this in the 9.6 branch and leaving it turned on
> in master, with the hope of shipping it enabled-by-default in v10.

​My initial reaction was +1 but now I'm leaning toward enabled by default.

Those who would upgrade to 9.6 within a year of its release are most
likely, process and personality wise, to be those for whom the risks and
rewards of new features is part of their everyday routine.

If indeed we release 10.0 with it enabled by default we should be confident
in its stability at that point in the 9.6.x branch.

David J.​