Date: Wed, 12 Jun 2024 10:52:42 +0000
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, pgsql-hackers@lists.postgresql.org
Subject: Re: Track the amount of time waiting due to cost_delay
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Hi,

On Tue, Jun 11, 2024 at 11:40:36AM -0500, Nathan Bossart wrote:
> On Tue, Jun 11, 2024 at 07:25:11AM +0000, Bertrand Drouvot wrote:
> > So I think that in v2 we could: 1) measure the actual wait time instead, 2)
> > count the number of times the vacuum slept. We could also 3) reports the
> > effective cost limit (as proposed by Nathan up-thread) (I think that 3) could
> > be misleading but I'll yield to majority opinion if people think it's not).
> 
> I still think the effective cost limit would be useful, if for no other
> reason than to help reinforce that it is distributed among the autovacuum
> workers.

I also think it can be useful, my concern is more to put this information in
pg_stat_progress_vacuum. What about Sawada-san proposal in [1]? (we could
create a new view that would contain those data: per-worker dobalance, cost_lmit,
cost_delay, active, and failsafe). 

[1]: https://www.postgresql.org/message-id/CAD21AoDOu%3DDZcC%2BPemYmCNGSwbgL1s-5OZkZ1Spd5pSxofWNCw%40mail.gmail.com

Regards,

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