On Tue, May 31, 2016 at 11:22 AM, Josh berkus <josh@agliodbs.com> wrote:
>> I think we can hope that developers are going to be less confused about
>> that than users.
>
> Makes sense.
Maybe EXPLAIN doesn't have to use the term parallel worker at all. It
can instead use a slightly broader terminology, possibly including the
term "core".
> One more consistency question: what's the effect of running out of
> max_parallel_workers?
>
> That is, say max_parallel_workers is set to 10, and 8 are already
> allocated. If I ask for max_parallel_X = 4, how many cores to I use?
Well, it depends on the planner, of course. But when constrained only
by the availability of worker processes, then your example could use 3
cores -- the 2 remaining parallel workers, plus the leader itself.
> Presumably the leader isn't counted towards max_parallel_workers?
Exactly.
--
Peter Geoghegan
