Re: Rename max_parallel_degree?

David G. Johnston <david.g.johnston@gmail.com>

From: "David G. Johnston" <david.g.johnston@gmail.com>

To: Peter Geoghegan <pg@heroku.com>

Cc: Josh berkus <josh@agliodbs.com>, Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>, Noah Misch <noah@leadboat.com>, David Rowley <david.rowley@2ndquadrant.com>, Amit Kapila <amit.kapila16@gmail.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Magnus Hagander <magnus@hagander.net>, Bruce Momjian <bruce@momjian.us>, PostgreSQL-development <pgsql-hackers@postgresql.org>

Date: 2016-05-31T18:17:35Z

Lists: pgsql-hackers

On Tuesday, May 31, 2016, Peter Geoghegan <pg@heroku.com> wrote:

> On Tue, May 31, 2016 at 11:02 AM, Josh berkus <josh@agliodbs.com
> <javascript:;>> wrote:
> > I get where you're coming from, but I think Haas's query plan output is
> > going to show us the confusion we're going to get.  So we need to either
> > change the parameter, the explain output, or brace ourselves for endless
> > repeated questions.
>
> I get where you're coming from, too -- I think our positions are very
> close.
>
> The only reason I favor defining parallel_degree = 1, rather than
> doing what Tom proposes to do with that patch, is that we might as
> well use the prevailing terminology used by SQL Server and Oracle (as
> long as we match those semantics). Also, I think that number of cores
> used is a more important consideration for users than the number of
> workers used.
>
> Users will definitely be confused about workers used vs. cores used,
> but I don't think that any proposal fixes that.
>
>
Ideally each worker gets its own core - though obviously physical
limitations apply.  If that's not the case then, yes, at least one user is
confused...

David J.