Re: Rename max_parallel_degree?

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Peter Geoghegan <pg(at)heroku(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Josh Berkus <josh(at)agliodbs(dot)com>, "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Noah Misch <noah(at)leadboat(dot)com>, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Magnus Hagander <magnus(at)hagander(dot)net>, Bruce Momjian <bruce(at)momjian(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Rename max_parallel_degree?
Date: 2016-06-09 20:08:57
Message-ID: CA+TgmoZ4MdcMR7XC_6t1LfHhSskwX5h2Wris58b=gBHFJjjfUw@mail.gmail.com
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On Thu, Jun 9, 2016 at 2:05 PM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:
> On Thu, Jun 9, 2016 at 7:04 AM, Robert Haas <robertmhaas(at)gmail(dot)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

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