Horton

Re: Track the amount of time waiting due to cost_delay

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2024-06-11T08:26:23Z
Lists: pgsql-hackers

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  1. Add delay time to VACUUM/ANALYZE (VERBOSE) and autovacuum logs.

  2. Add cost-based vacuum delay time to progress views.

  3. Add is_analyze parameter to vacuum_delay_point().

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

Hi,

On Tue, Jun 11, 2024 at 04:07:05PM +0900, Masahiko Sawada wrote:

> Thank you for the proposal and the patch. I understand the motivation
> of this patch.

Thanks for looking at it!

> Beside the point Nathan mentioned, I'm slightly worried
> that massive parallel messages could be sent to the leader process
> when the cost_limit value is low.

I see, I can/will do some testing in this area and share the numbers.

> 
> FWIW when I want to confirm the vacuum delay effect, I often use the
> information from the DEBUG2 log message in VacuumUpdateCosts()
> function. Exposing these data (per-worker dobalance, cost_lmit,
> cost_delay, active, and failsafe) somewhere in a view might also be
> helpful for users for checking vacuum delay effects.

Do you mean add time_delayed in pg_stat_progress_vacuum and cost_limit + the
other data you mentioned above in another dedicated view?

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com