| From: | Julien Rouhaud <julien(dot)rouhaud(at)dalibo(dot)com> |
|---|---|
| To: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
| Cc: | James Sewell <james(dot)sewell(at)lisasoft(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Choosing parallel_degree |
| Date: | 2016-03-17 11:30:47 |
| Message-ID: | 56EA9567.5090801@dalibo.com |
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| Lists: | pgsql-hackers |
On 17/03/2016 12:21, David Rowley wrote:
> On 18 March 2016 at 00:13, Julien Rouhaud <julien(dot)rouhaud(at)dalibo(dot)com> wrote:
>> With the current threshold, you need a table bigger than 8 MB to be able
>> to force parallel workers. I'm not sure there'll be benefits for
>> multiple workers on a table smaller than 8 MB, since setting up all the
>> parallel stuff takes time.
>
> It would be really nice if it were possible to drop the setting really
> low, so that combined with a low parallel_setup_cost we could enable
> parallel query on small tables in the regression test suite.
>
>
Indeed. That could also be a use case for moving parallel_threshold to a
GUC, but not sure what'd be best.
--
Julien Rouhaud
http://dalibo.com - http://dalibo.org
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