Re: Track the amount of time waiting due to cost_delay - Mailing list pgsql-hackers

From Nathan Bossart
Subject Re: Track the amount of time waiting due to cost_delay
Date
Msg-id Z1iAnSYHZ6j5u2Fv@nathan
Whole thread Raw
In response to Re: Track the amount of time waiting due to cost_delay  (Bertrand Drouvot <bertranddrouvot.pg@gmail.com>)
Responses Re: Track the amount of time waiting due to cost_delay
Re: Track the amount of time waiting due to cost_delay
List pgsql-hackers
On Mon, Dec 09, 2024 at 04:41:03PM +0000, Bertrand Drouvot wrote:
> +       <structfield>time_delayed</structfield> <type>bigint</type>

I think it's also worth considering names like total_delay and
cumulative_delay.

> +       Total amount of time spent in milliseconds waiting during <xref linkend="guc-vacuum-cost-delay"/>
> +       or <xref linkend="guc-autovacuum-vacuum-cost-delay"/>. In case of parallel
> +       vacuum the reported time is across all the workers and the leader. The
> +       workers update the column no more frequently than once per second, so it
> +       could show slightly old values.

I wonder if it makes sense to provide this value as an interval instead of
the number of milliseconds to make it more human-readable.  I might also
suggest some changes to the description:

    Total accumulated time spent sleeping due to the cost-based vacuum
    delay settings (e.g., vacuum_cost_delay, vacuum_cost_limit).  This
    includes the time that any associated parallel workers have slept, too.
    However, parallel workers report their sleep time no more frequently
    than once per second, so the reported value may be slightly stale.

-- 
nathan



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