Re: cost based vacuum (parallel) - Mailing list pgsql-hackers

From Andres Freund
Subject Re: cost based vacuum (parallel)
Date
Msg-id 20191104190818.kbvcris4dynrjd6u@alap3.anarazel.de
Whole thread Raw
In response to Re: cost based vacuum (parallel)  (Stephen Frost <sfrost@snowman.net>)
Responses Re: cost based vacuum (parallel)  (Stephen Frost <sfrost@snowman.net>)
List pgsql-hackers
Hi,

On 2019-11-04 14:06:19 -0500, Stephen Frost wrote:
> * Jeff Janes (jeff.janes@gmail.com) wrote:
> > On Mon, Nov 4, 2019 at 1:54 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > > For parallel vacuum [1], we were discussing what is the best way to
> > > divide the cost among parallel workers but we didn't get many inputs
> > > apart from people who are very actively involved in patch development.
> > > I feel that we need some more inputs before we finalize anything, so
> > > starting a new thread.
> > 
> > Maybe a I just don't have experience in the type of system that parallel
> > vacuum is needed for, but if there is any meaningful IO throttling which is
> > active, then what is the point of doing the vacuum in parallel in the first
> > place?
> 
> With parallelization across indexes, you could have a situation where
> the individual indexes are on different tablespaces with independent
> i/o, therefore the parallelization ends up giving you an increase in i/o
> throughput, not just additional CPU time.

How's that related to IO throttling being active or not?

Greetings,

Andres Freund



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