Re: cost based vacuum (parallel)

On Tue, Nov 5, 2019 at 1:12 AM Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2019-11-04 14:33:41 -0500, Stephen Frost wrote:
>
> > I've been wondering if the accounting system should consider the cost
> > per tablespace when there's multiple tablespaces involved, instead of
> > throttling the overall process without consideration for the
> > per-tablespace utilization.
>
> This all seems like a feature proposal, or two, independent of the
> patch/question at hand. I think there's a good argument to be had that
> we should severely overhaul the current vacuum cost limiting - it's way
> way too hard to understand the bandwidth that it's allowed to
> consume. But unless one of the proposals makes that measurably harder or
> easier, I think we don't gain anything by entangling an already complex
> patchset with something new.
>

+1. I think even if we want something related to per-tablespace
costing for vacuum (parallel), it should be done as a separate patch.
It is a whole new area where we need to define what is the appropriate
way to achieve. It is going to change the current vacuum costing
system in a big way which I don't think is reasonable to do as part of
a parallel vacuum patch.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com