Re: Track the amount of time waiting due to cost_delay

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