Re: Track the amount of time waiting due to cost_delay

> I'm not convinced that reporting the number of waits is useful. If we
> were going to report a possibly-inaccurate amount of actual waiting,
> then also reporting the number of waits might make it easier to figure
> out when the possibly-inaccurate number was in fact inaccurate. But I
> think it's way better to report an accurate amount of actual waiting,
> and then I'm not sure what we gain by also reporting the number of
> waits.

I think including the number of times vacuum went into sleep
will help paint a full picture of the effect of tuning the vacuum_cost_delay
and vacuum_cost_limit for the user, even if we are reporting accurate
amounts of actual sleeping.

This is particularly true for autovacuum in which the cost limit is spread
across all autovacuum workers, and knowing how many times autovacuum
went to sleep will be useful along with the total time spent sleeping.

Regards,

Sami