Subject: Re: Rename max_parallel_degree?
To: Petr Jelinek <petr@2ndquadrant.com>,
 "David G. Johnston" <david.g.johnston@gmail.com>
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Cc: Jim Nasby <Jim.Nasby@bluetreble.com>, Robert Haas
 <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>,
 Alvaro Herrera <alvherre@2ndquadrant.com>, Josh berkus <josh@agliodbs.com>,
 Peter Geoghegan <pg@heroku.com>, Noah Misch <noah@leadboat.com>,
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 Amit Kapila <amit.kapila16@gmail.com>, Magnus Hagander
 <magnus@hagander.net>, Bruce Momjian <bruce@momjian.us>,
 PostgreSQL-development <pgsql-hackers@postgresql.org>
From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Organization: 2ndQuadrant
Message-ID: <a2fffd92-6e59-a4eb-dd85-c5865ebca1a0@2ndquadrant.com>
Date: Fri, 3 Jun 2016 00:33:02 -0400
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On 6/3/16 12:21 AM, Petr Jelinek wrote:
> On 01/06/16 17:55, David G. Johnston wrote:
>> On Wed, Jun 1, 2016 at 11:45 AM, Petr Jelinek <petr@2ndquadrant.com
>> <mailto:petr@2ndquadrant.com>>wrote:
>>
>>     That GUC also controls worker processes that are started by
>>     extensions, not just ones that parallel query starts. This is btw
>>     one thing I don't like at all about how the current limits work, the
>>     parallel query will fight for workers with extensions because they
>>     share the same limit.
>>
>>
>> ​Given that this models reality the GUC is doing its job.  Now, maybe we
>> need additional knobs to give the end-user the ability to influence how
>> those fights will turn out.
>
> Agreed, my point is that I think we do need additional knob.

We need one knob to control how many process slots to create at server 
start, and then a bunch of sliders to control how to allocate those 
between regular connections, superuser connections, replication, 
autovacuum, parallel workers, background workers (by tag/label/group), 
and so on.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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