|From:||Andres Freund <andres(at)anarazel(dot)de>|
|Subject:||Why does [auto-]vacuum delay not report a wait event?|
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I was looking at , wanting to suggest a query to monitor what
autovacuum is mostly waiting on. Partially to figure out whether it's
mostly autovacuum cost limiting.
But uh, unfortunately the vacuum delay code just sleeps without setting
a wait event:
/* Nap if appropriate */
if (msec > 0)
if (msec > VacuumCostDelay * 4)
msec = VacuumCostDelay * 4;
pg_usleep((long) (msec * 1000));
Seems like it should instead use a new wait event in the PG_WAIT_TIMEOUT
Given how frequently we run into trouble with [auto]vacuum throttling
being a problem, and there not being any way to monitor that currently,
that seems like it'd be a significant improvement, given the effort?
It'd probably also be helpful to report the total time [auto]vacuum
spent being delayed for vacuum verbose/autovacuum logging, but imo
that'd be a parallel feature to a wait event, not a replacement.
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