Horton

Re: Should we increase the default vacuum_cost_limit?

Andrew Dunstan <andrew.dunstan@2ndquadrant.com>

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From: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
To: David Rowley <david.rowley@2ndquadrant.com>, Joe Conway <mail@joeconway.com>
Cc: Peter Geoghegan <pg@bowt.ie>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-03-05T22:14:55Z
Lists: pgsql-hackers 
On 2/25/19 8:38 AM, David Rowley wrote:
> 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.
>

This patch is tiny, seems perfectly reasonable, and has plenty of
support. I'm going to commit it shortly unless there are last minute
objections.


cheers


andrew



-- 
Andrew Dunstan                https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, 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