From: Tom Lane <tgl@sss.pgh.pa.us>
To: Josh berkus <josh@agliodbs.com>
cc: Peter Geoghegan <pg@heroku.com>, 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>
Subject: Re: Rename max_parallel_degree?
In-reply-to: <574DC881.5010006@agliodbs.com>
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Comments: In-reply-to Josh berkus <josh@agliodbs.com>
	message dated "Tue, 31 May 2016 10:23:13 -0700"
Date: Tue, 31 May 2016 13:30:36 -0400
Message-ID: <9816.1464715836@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-hackers-owner@postgresql.org

Josh berkus <josh@agliodbs.com> writes:
> On 05/31/2016 10:16 AM, Peter Geoghegan wrote:
>> But the distinction between parallel workers and backends that can
>> participate in parallel query does need to be user-visible. Worker
>> processes are a commodity (i.e. the user must consider
>> max_worker_processes).

> It's still WAY simpler to understand "max_parallel is the number of
> parallel workers I requested".

> Any system where you set it to 2 and get only 1 worker on an idle system
> is going to cause endless queries on the mailing lists.

I really think that a GUC named "max_parallel_workers", which in fact
limits the number of workers and not something else, is the way to go.

			regards, tom lane


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