From: | Masahiko Sawada <masahiko(dot)sawada(at)2ndquadrant(dot)com> |
---|---|
To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, David Rowley <dgrowleyml(at)gmail(dot)com>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: VACUUM PARALLEL option vs. max_parallel_maintenance_workers |
Date: | 2020-10-05 05:36:43 |
Message-ID: | CA+fd4k6yTi-f089J+4nW5a2DPQBJ7pTgqpHQvO-9+xtdJmV4rg@mail.gmail.com |
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On Mon, 5 Oct 2020 at 11:21, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> On Sat, Oct 3, 2020 at 9:25 AM Masahiko Sawada
> <masahiko(dot)sawada(at)2ndquadrant(dot)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
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