Re: cost based vacuum (parallel)

Hi,

On 2019-11-04 14:06:19 -0500, Stephen Frost wrote:
> * Jeff Janes (jeff(dot)janes(at)gmail(dot)com) wrote:
> > On Mon, Nov 4, 2019 at 1:54 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)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