Horton

Re: Should vacuum process config file reload more often

Daniel Gustafsson <daniel@yesql.se>

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From: Daniel Gustafsson <daniel@yesql.se>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Melanie Plageman <melanieplageman@gmail.com>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Andres Freund <andres@anarazel.de>, amit.kapila16@gmail.com
Date: 2023-03-30T19:26:47Z
Lists: pgsql-hackers 
> On 30 Mar 2023, at 04:57, Masahiko Sawada <sawada.mshk@gmail.com> wrote:

> As another idea, why don't we use macros for that? For example,
> suppose VacuumCostStatus is like:
> 
> typedef enum VacuumCostStatus
> {
>    VACUUM_COST_INACTIVE_LOCKED = 0,
>    VACUUM_COST_INACTIVE,
>    VACUUM_COST_ACTIVE,
> } VacuumCostStatus;
> VacuumCostStatus VacuumCost;
> 
> non-vacuum code can use the following macros:
> 
> #define VacuumCostActive() (VacuumCost == VACUUM_COST_ACTIVE)
> #define VacuumCostInactive() (VacuumCost <= VACUUM_COST_INACTIVE) //
> or we can use !VacuumCostActive() instead.

I'm in favor of something along these lines.  A variable with a name that
implies a boolean value (active/inactive) but actually contains a tri-value is
easily misunderstood.  A VacuumCostState tri-value variable (or a better name)
with a set of convenient macros for extracting the boolean active/inactive that
most of the code needs to be concerned with would more for more readable code I
think.

--
Daniel Gustafsson

Commits

  1. Fix assertion failure in heap_vacuum_rel

  2. Fix vacuum_cost_delay check for balance calculation.

  3. Fix autovacuum cost debug logging

  4. Refresh cost-based delay params more frequently in autovacuum

  5. Separate vacuum cost variables from GUCs

  6. Make vacuum failsafe_active globally visible

  7. Don't balance vacuum cost delay when per-table settings are in effect