Re: Autovacuum in the backend

Hannu Krosing wrote:

>Can autovacuum yet be configured _not_ to run vacuum during some hours
>or above some load ?
>
>

That is certainly a goal, hopefully it will get done for 8.1. The
actual design I had in mind (based on prior discussion on hackers) is to
allow a maintenance window that would have lower vacuum thresholds, this
way only the tables that really need it will get vacuumed during the day.

>Even better - to stop or pause a long-running vacuum if load goes above
>some limit.
>
>

I don't think the current implementation if VACUUM can support that. I
believe that all the work will get rolled back if gets canceled.

Perhaps a decent solution would be to have autovacuum increase the
vacuum delay settings dynamically based on system load average. That
way if a vacuum starts and the system starts to get busy, the autoavcuum
daemon can increase the vacuum delay settings and VACUUM would honor
this while running.

>If it goes into backend before the above is done, it should at least be
>possible to switch it off completely.
>
>

Absolutely, in fact it will not only have the option to turn it off, it
will be off by default.