Re: Rename max_parallel_degree?

Robert Haas wrote:
> On Wed, Jun 1, 2016 at 5:29 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> >> I've largely given up hope of coming up with an alternative that can
> >> attract more than one vote and that is also at least mildly accurate,
> >> but one idea is max_parallel_workers_per_gather_node. That will be
> >> totally clear.
> >
> > Given the reference to Gather nodes, couldn't you drop the word
> > "parallel"? "node" might not be necessary either.
>
> Well, I think we could drop node, if you like. I think parallel
> wouldn't be good to drop, though, because it sounds like we want a
> global limit on parallel workers also, and that can't be just
> max_workers. So I think we should keep parallel in there for all of
> them, and have max_parallel_workers and
> max_parallel_workers_per_gather(_node). The reloption and the Path
> struct field can be parallel_workers rather than parallel_degree.

I believe that it will be impossible to find a name that makes
the meaning clear to everybody. Those who do not read the documentation
will always find a way to misunderstand it.

These suggestions have the added disadvantage that it is hard
to remember them. I see myself going, "I have to change the maximum
for parallel workers, what was the name again?", and having to resort
to the manual (or SHOW ALL) each time.

I suggest to follow the precedent of "work_mem", stick with
something simple like "max_parallel_workers" and accept the risk
of not being totally self-explanatory.

Yours,
Laurenz Albe