pg.ddx.io  pgsql-hackers@postgresql.org mailing list archive  

help / color / mirror / Atom feed
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Geoghegan <pg@heroku.com>
Cc: Josh berkus <josh@agliodbs.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Noah Misch <noah@leadboat.com>
Cc: David Rowley <david.rowley@2ndquadrant.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Magnus Hagander <magnus@hagander.net>
Cc: Bruce Momjian <bruce@momjian.us>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Rename max_parallel_degree?
Date: Tue, 31 May 2016 14:08:57 -0400
Message-ID: <21507.1464718137@sss.pgh.pa.us> (raw)
In-Reply-To: <CAM3SWZQTmjE+O-NnGthzLd61RtXkNfitWrZU6zJHHHZSB3YmEg@mail.gmail.com>
References: <20160426152217.GA548975@alvherre.pgsql>
	<20160529053300.GD496776@tornado.leadboat.com>
	<CA+TgmoYqLP6dPpcLvWU-ToJFNn4Dp3NE2qAmgXprKN3S6wTSFw@mail.gmail.com>
	<WM!782dde02eb02f131fac86b9aa0affdd2fa2450ae598af9554b103693ecd60442e44967d03f38f3b7cda9ff5b35da9166!@mailstronghold-2.zmailcloud.com>
	<574DBEA4.9000205@agliodbs.com>
	<8716.1464714201@sss.pgh.pa.us>
	<WM!fa29cdfaada6f23ea036083b3b09c992113c0dd0d39c12a9cb6f842c5da62c7ec3f6f29cf1a792b4d2a344288b7c1492!@mailstronghold-2.zmailcloud.com>
	<574DC585.7010507@agliodbs.com>
	<CAM3SWZR6cd4v-LMmu9hoMR0pRVH9hKPSchEyH=v6BOo7OdhY5Q@mail.gmail.com>
	<WM!4d4bffdc428f6cc6f750204a44dd53cae60035c32efd88a025cf336cd84efaf89a3b03b6e585b4ba6d94b14cd3339b6b!@mailstronghold-3.zmailcloud.com>
	<574DC881.5010006@agliodbs.com>
	<CAM3SWZS_zL8Wx-zdo_LBJu4ggVqSQZrB_be2Ht1euWQ_AbLerA@mail.gmail.com>
	<WM!03d2e4eb6a54be412896ebf7a163e0e3ca3c30ba669ab43e75f184e0eb3fee6c99a96f58b016bffa9bc4be5b1606e6be!@mailstronghold-3.zmailcloud.com>
	<574DCDFC.6060! 506@agliodbs.com>
	<CAM3SWZQTmjE+O-NnGthzLd61RtXkNfitWrZU6zJHHHZSB3YmEg@mail.gmail.com>
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-hackers>

Peter Geoghegan <pg@heroku.com> writes:
> Even when the leader is consuming input from workers, that's still perhaps
> pegging one CPU core. So, it doesn't really invalidate what I said about
> the number of cores being the primary consideration.

Agreed, but if we think that people need to be thinking in those terms,
maybe the parameter should be "max_parallel_cores".

The alternate docs patch I just posted tries to deal with this by
describing max_parallel_workers as being the max number of worker
processes used to "assist" a parallel query.  That was terminology
already being used in one place, but not consistently.  If we use it
consistently, I think it would be sufficient to remind people that
they need to figure on one more core for the leader.

			regards, tom lane


-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers



view thread (185+ messages)  latest in thread

Message-ID: <21507.1464718137@sss.pgh.pa.us>
Permalink:  ../21507.1464718137@sss.pgh.pa.us/
Also on:    postgresql.org/message-id/21507.1464718137@sss.pgh.pa.us

 · 

reply
Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: pgsql-hackers@postgresql.org
  Cc: tgl@sss.pgh.pa.us, pg@heroku.com, josh@agliodbs.com, robertmhaas@gmail.com, noah@leadboat.com, david.rowley@2ndquadrant.com, amit.kapila16@gmail.com, alvherre@2ndquadrant.com, magnus@hagander.net, bruce@momjian.us
  Subject: Re: Rename max_parallel_degree?
  In-Reply-To: <21507.1464718137@sss.pgh.pa.us>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox