Horton

Re: Should we increase the default vacuum_cost_limit?

David Rowley <david.rowley@2ndquadrant.com>

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From: David Rowley <david.rowley@2ndquadrant.com>
To: Joe Conway <mail@joeconway.com>
Cc: Peter Geoghegan <pg@bowt.ie>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-02-25T13:38:59Z
Lists: pgsql-hackers

Attachments

On Tue, 26 Feb 2019 at 02:06, Joe Conway <mail@joeconway.com> wrote:
>
> On 2/25/19 1:17 AM, Peter Geoghegan wrote:
> > On Sun, Feb 24, 2019 at 9:42 PM David Rowley
> > <david.rowley@2ndquadrant.com> wrote:
> >> The current default vacuum_cost_limit of 200 seems to be 15 years old
> >> and was added in f425b605f4e.
> >>
> >> Any supporters for raising the default?
> >
> > I also think that the current default limit is far too conservative.
>
> I agree entirely. In my experience you are usually much better off if
> vacuum finishes quickly. Personally I think our default scale factors
> are horrible too, especially when there are tables with large numbers of
> rows.

Agreed that the scale factors are not perfect, but I don't think
changing them is as quite a no-brainer as the vacuum_cost_limit, so
the attached patch just does the vacuum_cost_limit.

I decided to do the times by 10 option that I had mentioned.... Ensue
debate about that...

I'll add this to the March commitfest and set the target version as PG12.

-- 
 David Rowley                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

Commits

  1. Allow fractional input values for integer GUCs, and improve rounding logic.

  2. Reduce the default value of autovacuum_vacuum_cost_delay to 2ms.

  3. Revert "Increase the default vacuum_cost_limit from 200 to 2000"

  4. Convert [autovacuum_]vacuum_cost_delay into floating-point GUCs.

  5. Include GUC's unit, if it has one, in out-of-range error messages.

  6. Disallow NaN as a value for floating-point GUCs.

  7. Increase the default vacuum_cost_limit from 200 to 2000