Subject: Re: max_worker_processes default not documented
To: "David G. Johnston" <david.g.johnston@gmail.com>
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From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Organization: 2ndQuadrant
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Date: Tue, 2 Aug 2016 13:57:15 -0400
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On 5/12/16 9:24 AM, David G. Johnston wrote:
>  Thanks.  Now for a related question.  Are any of those workers
> permanently in use?  And what processes use them.  I can think of
> checkpoint writer and autovacuum off the top of my head that are
> potential candidates.

max_worker_processes only controls "background workers".  The other
facilities you mention don't count as such (confusingly perhaps).

Before 9.6, the only background workers were from extensions.  In 9.6,
the parallel workers also use the background worker facilities and count
against max_worker_processes.

More documentation is possible here.  I think maybe a section somewhere
that summarizes all the parallel-related settings.  And also something
in the release notes noting that max_worker_processes is now also used
by built-in facilities, so you should increase it if you have previously
adjusted it for something.

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


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