Re: VACUUM PARALLEL option vs. max_parallel_maintenance_workers - Mailing list pgsql-hackers

From Masahiko Sawada
Subject Re: VACUUM PARALLEL option vs. max_parallel_maintenance_workers
Date
Msg-id CA+fd4k6yTi-f089J+4nW5a2DPQBJ7pTgqpHQvO-9+xtdJmV4rg@mail.gmail.com
Whole thread Raw
In response to Re: VACUUM PARALLEL option vs. max_parallel_maintenance_workers  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
On Mon, 5 Oct 2020 at 11:21, Robert Haas <robertmhaas@gmail.com> wrote:
>
> On Sat, Oct 3, 2020 at 9:25 AM Masahiko Sawada
> <masahiko.sawada@2ndquadrant.com> wrote:
> > To make the behavior of parallel vacuum more consistent with other
> > parallel maintenance commands (i.g., only parallel INDEX CREATE for
> > now), as a second idea, can we make use of parallel_workers reloption
> > in parallel vacuum case as well?
>
> That seems like a terrible idea to me. I don't see why the number of
> workers that some user thinks should be used to perform a scan on the
> table as part of the query should be the same as the number of workers
> that should be used for a maintenance operation.

Agreed. But the same is true for parallel REINDEX? It's also a
maintenance operation.

In any case, the thing would get more complex if lazy vacuum or vacuum
full were to support parallel operation on table scan in the future.

Regards,

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



pgsql-hackers by date:

Previous
From: Kyotaro Horiguchi
Date:
Subject: Re: Asynchronous Append on postgres_fdw nodes.
Next
From: Dilip Kumar
Date:
Subject: Re: [HACKERS] Custom compression methods