Re: max_parallel_workers can't actually be set?

From: Andres Freund <andres(at)anarazel(dot)de>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: max_parallel_workers can't actually be set?
Date: 2019-08-17 20:28:19
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On 2019-08-17 13:41:18 -0400, Tom Lane wrote:
> Try this:
> alter system set max_parallel_workers = 20;
> and restart the system.
> max_parallel_workers is still 8, according to both SHOW and
> pg_controldata, nor can you launch more than 8 workers.

Hm. I can't reproduce that. I do get whatever number I configure. Note
also that pg_controldata shows max_worker_processes, not

> Even odder, if you just do
> regression=# set max_parallel_workers = 200;
> regression=# show max_parallel_workers;
> max_parallel_workers
> ----------------------
> 200
> (1 row)
> which should certainly not happen for a PGC_POSTMASTER parameter.

It's not PGC_POSTMASTER. That's max_worker_processes. The max_parallel_*
GUCs just control how many of max_worker_processes are used for $task.


Andres Freund

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