From: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> |
---|---|
To: | Peter Geoghegan <pg(at)bowt(dot)ie> |
Cc: | PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: vacuum_cost_page_miss default value and modern hardware |
Date: | 2021-01-15 04:33:38 |
Message-ID: | CAD21AoDjJt8Pt3UvvWFaCpFBm+3+nrKwt6qKruO5gWwhO9VB3A@mail.gmail.com |
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On Thu, Jan 14, 2021 at 9:24 AM Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
>
> On Wed, Jan 6, 2021 at 7:43 PM Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> > More concretely, we could perhaps lower vacuum_cost_page_miss to 5. It
> > has had the value as 10 as its default since 2004 (just like
> > vacuum_cost_page_dirty, whose default has also not been changed since
> > the start). These defaults were decided in a time when nbtree VACUUM
> > could do lots of random I/O, there was no visibility map, etc. So this
> > refresh is not just about hardware.
>
> Attached patch lowers vacuum_cost_page_miss to 3. I think that this
> change in the default is both likely to be helpful in medium to large
> installations, and unlikely to cause harm in small installations. If
> I/O for reads made by VACUUM is naturally very slow (even in the
> common case where it's entirely sequential), then that will naturally
> provide additional throttling.
+1 for this change. Lowering to 2 also looks good to me.
Regards,
--
Masahiko Sawada
EnterpriseDB: https://www.enterprisedb.com/
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