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From: Josh Berkus <josh@agliodbs.com>
To: Robert Haas <robertmhaas@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: David G. Johnston <david.g.johnston@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>
Cc: Peter Geoghegan <pg@heroku.com>
Cc: Noah Misch <noah@leadboat.com>
Cc: David Rowley <david.rowley@2ndquadrant.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: Wed, 8 Jun 2016 08:56:35 -0400
Message-ID: <57581603.3040309@agliodbs.com> (raw)
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On 06/07/2016 11:01 PM, Robert Haas wrote:
> On Fri, Jun 3, 2016 at 9:39 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Robert Haas <robertmhaas@gmail.com> writes:
>>> I think we should just go with max_parallel_workers for a limit on
>>> total parallel workers within max_work_processes, and
>>> max_parallel_workers_per_gather for a per-Gather limit.  It's slightly
>>> annoying that we may end up renaming the latter GUC, but not as
>>> annoying as spending another three weeks debating this and missing
>>> beta2.
>>
>> +1.  I'm not as convinced as you are that we'll replace the GUC later,
>> but in any case this is an accurate description of the current
>> semantics.  And I'm really *not* in favor of fudging the name with
>> the intent of changing the GUC's semantics later --- that would fail
>> all sorts of compatibility expectations.
> 
> Here's a patch change max_parallel_degree to
> max_parallel_workers_per_gather, and also changing parallel_degree to
> parallel_workers.  I haven't tackled adding a separate
> max_parallel_workers, at least not yet.  Are people OK with this?

+1

> 
> Note that there is a dump/restore hazard if people have set the
> parallel_degree reloption on a beta1 install, or used ALTER { USER |
> DATABASE } .. SET parallel_degree.  Can everybody live with that?
> Should I bump catversion when applying this?

IMHO, we just need to call it out in the beta2 announcement.


-- 
--
Josh Berkus
Red Hat OSAS
(any opinions are my own)


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