Re: Adjust autovacuum naptime automatically

ITAGAKI Takahiro wrote:

> In the case of a heavily update workload, the default naptime (60 seconds)
> is too long to keep the number of dead tuples low. With my patch, the naptime
> will be adjusted around 3 seconds at the case of pgbench (scale=10, 80 tps)
> with default other autovacuum parameters.

Interesting. To be frank I don't know what the sleep scale factor was
supposed to do.

> I have something that I want to discuss with you:
> - Can we use the process-exitcode to make autovacuum daemon to communicate
> with postmaster? I used it to notify there are any vacuum jobs or not.

I can only tell you we do this is Mammoth Replicator and it works for
us. Whether this is a very good idea, I don't know. I didn't find any
other means to communicate stuff from dying processes to the postmaster.

> - I removed autovacuum_naptime guc variable, because it is adjusted
> automatically now. Is it appropriate?

I think we should provide the user with a way to stop the naptime from
changing at all. Eventually we will have the promised "maintenance
windows" feature which will mean the user will not have to worry at all
about the naptime, but in the meantime I think we should keep it.

--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support