| From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
|---|---|
| To: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> |
| Cc: | Mahendra Singh <mahi6run(at)gmail(dot)com>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, Robert Haas <robertmhaas(at)gmail(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, David Steele <david(at)pgmasters(dot)net>, Claudio Freire <klaussfreire(at)gmail(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] Block level parallel vacuum |
| Date: | 2019-10-17 08:30:21 |
| Message-ID: | CAA4eK1KJj4_zwuhLX_giR1ReAYyoF1bW6EyBoU4fh1QdekBeOw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Oct 17, 2019 at 12:21 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Thu, Oct 17, 2019 at 10:56 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> >
> > I guess that the concepts of vacuum delay contradicts the concepts of
> > parallel vacuum. The concepts of parallel vacuum would be to use more
> > resource to make vacuum faster. Vacuum delays balances I/O during
> > vacuum in order to avoid I/O spikes by vacuum but parallel vacuum
> > rather concentrates I/O in shorter duration.
> >
>
> You have a point, but the way it is currently working in the patch
> doesn't make much sense.
>
Another point in this regard is that the user anyway has an option to
turn off the cost-based vacuum. By default, it is anyway disabled.
So, if the user enables it we have to provide some sensible behavior.
If we can't come up with anything, then, in the end, we might want to
turn it off for a parallel vacuum and mention the same in docs, but I
think we should try to come up with a solution for it.
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com
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