Date: Mon, 9 Jul 2018 11:19:28 -0400
From: Bruce Momjian <bruce@momjian.us>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Justin Pryzby <pryzby@telsasoft.com>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: add default parallel query to v10 release notes? (Re: [PERFORM]
 performance drop after upgrade (9.6 > 10))
Message-ID: <20180709151928.GB19710@momjian.us>
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 <CA++JNSfTEifSiBq73zpGCQuDNGr9yYcjmkx_=LtAbnadKLY_vg@mail.gmail.com>
 <20171026194515.GV21735@telsasoft.com>
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On Fri, Jun 22, 2018 at 02:53:36PM +0530, Amit Kapila wrote:
> On Wed, Jun 20, 2018 at 8:43 PM, Bruce Momjian <bruce@momjian.us> wrote:
> > On Thu, May 24, 2018 at 08:00:25PM -0500, Justin Pryzby wrote:
> >
> > So I did some research on this, particularly to find out how it was
> > missed in the PG 10 release notes.  It turns out that
> > max_parallel_workers_per_gather has always defaulted to 2 in head, and
> > this was changed to default to 0 in the 9.6 branch:
> >
> >         commit f85b1a84152f7bf019fd7a2c5eede97867dcddbb
> >         Author: Robert Haas <rhaas@postgresql.org>
> >         Date:   Tue Aug 16 08:09:15 2016 -0400
> >
> >             Disable parallel query by default.
> >
> >             Per discussion, set the default value of max_parallel_workers_per_gather
> >             to 0 in 9.6 only.  We'll leave it enabled in master so that it gets
> >             more testing and in the hope that it can be enable by default in v10.
> >
> > Therefore, there was no commit to find in the PG 10 commit logs.  :-O
> > Not sure how we can avoid this kind of problem in the future.
> >
> > The attached patch adds a PG 10.0 release note item about this change.
> >
> 
> Your proposed text looks good to me.

Done, thanks.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +