Re: Rename max_parallel_degree?

From: Julien Rouhaud <julien(dot)rouhaud(at)dalibo(dot)com>
To: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, 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>, Peter Geoghegan <pg(at)heroku(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: 2016-06-29 06:24:23
Message-ID: 20312f33-c14e-0d3f-a79f-95212f64a38c@dalibo.com
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On 29/06/2016 06:29, Amit Kapila wrote:
> On Wed, Jun 29, 2016 at 2:57 AM, Julien Rouhaud
> <julien(dot)rouhaud(at)dalibo(dot)com> wrote:
>>
>> Thanks a lot for the help!
>>
>> PFA v6 which should fix all the issues mentioned.
>
> Couple of minor suggestions.
>
> - <xref linkend="guc-max-worker-processes">. Note that the requested
> + <xref linkend="guc-max-worker-processes">, limited by
> + <xref linked="guc-max-parallel-workers">. Note that the requested
>
> Typo.
> /linked/linkend
>

Oops, fixed.

> You can always find such mistakes by doing make check in doc/src/sgml/
>

I wasn't aware of that, it's really a nice thing to know, thanks!

> + /*
> + * We need a memory barrier here to make sure the above test doesn't get
> + * reordered
> + */
> + pg_read_barrier();
>
> /memory barrier/read barrier
>

fixed

> + if (max_parallel_workers == 0)
> + {
> + ereport(elevel,
> + (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
> + errmsg("background worker \"%s\": cannot request parallel worker if
> no parallel worker allowed",
>
> " ..no parallel worker is allowed". 'is' seems to be missing.
>

fixed

>
>> Also, after second
>> thought I didn't add the extra hint about max_worker_processes in the
>> max_parallel_worker paragraph, since this line was a duplicate of the
>> precedent paragraph, it seemed better to leave the text as is.
>>
>
> not a big problem, we can leave it for committer to decide on same.
> However just by reading the description of max_parallel_worker, user
> can set its value more than max_wroker_processes which we don't want.
>

Right. On the other hand I'm not sure that's really an issue, because
such a case is handled in the code, and setting max_parallel_workers way
above max_worker_processes could be a way to configure it as unlimited.
Or should we allow setting it to -1 for instance to disable the limit?

--
Julien Rouhaud
http://dalibo.com - http://dalibo.org

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