Re: Rename max_parallel_degree?

Robert Haas <robertmhaas@gmail.com>

From: Robert Haas <robertmhaas@gmail.com>
To: Peter Geoghegan <pg@heroku.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Josh Berkus <josh@agliodbs.com>, "David G. Johnston" <david.g.johnston@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Noah Misch <noah@leadboat.com>, David Rowley <david.rowley@2ndquadrant.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Magnus Hagander <magnus@hagander.net>, Bruce Momjian <bruce@momjian.us>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2016-06-09T20:08:57Z
Lists: pgsql-hackers
On Thu, Jun 9, 2016 at 2:05 PM, Peter Geoghegan <pg@heroku.com> wrote:
> On Thu, Jun 9, 2016 at 7:04 AM, Robert Haas <robertmhaas@gmail.com> wrote:
>> OK, I pushed this after re-reviewing it and fixing a number of
>> oversights.  There remains only the task of adding max_parallel_degree
>> as a system-wide limit (as opposed to max_parallel_degree now
>> max_parallel_workers_per_gather which is a per-Gather limit), which
>> I'm going to argue should be a new open item and not necessarily one
>> that I have to own myself.  I would like to take care of it, but I
>> will not put it ahead of fixing actual defects and I will not promise
>> to have it done in time for 9.6.
>
> I am in favor of having something similar to
> max_parallel_workers_per_gather for utility statements like CREATE
> INDEX. That will need a cost model, at least where the DBA isn't
> explicit about the number of workers to use.

We may well need that, but I think it should be discussed in
conjunction with the patches that add parallelism for those utility
statements, rather than discussing it on a thread for a 9.6 open item.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company