Horton

Re: Should we increase the default vacuum_cost_limit?

Tomas Vondra <tomas.vondra@2ndquadrant.com>

View thread View on postgr.es
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: David Rowley <david.rowley@2ndquadrant.com>
Cc: Peter Geoghegan <pg@bowt.ie>, Robert Haas <robertmhaas@gmail.com>, Joe Conway <mail@joeconway.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-03-06T20:26:49Z
Lists: pgsql-hackers 

On 3/6/19 12:10 AM, David Rowley wrote:
> Thanks for chipping in on this.
> 
> On Wed, 6 Mar 2019 at 01:53, Tomas Vondra <tomas.vondra@2ndquadrant.com> wrote:
>> But on the other hand it feels a bit weird that we increase this one
>> value and leave all the other (also very conservative) defaults alone.
> 
> Which others did you have in mind? Like work_mem, shared_buffers?  If
> so, I mentioned in the initial post that I don't see vacuum_cost_limit
> as in the same category as those.  It's not like PostgreSQL won't
> start on a tiny server if vacuum_cost_limit is too high, but you will
> have issues with too big a shared_buffers, for example.   I think if
> we insist that this patch is a review of all the "how big is your
> server" GUCs then that's raising the bar significantly and
> unnecessarily for what I'm proposing here.
> 

On second thought, I think you're right. It's still true that you need
to bump up various other GUCs on reasonably current hardware, but it's
true vacuum_cost_limit is special enough to increase it separately.

so +1 (I see Andrew already pushed it, but anyway ...)

-- 
Tomas Vondra                  http://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