Thread: AutoVacuum_NapTime

From:
"George Sexton"
Date:

I have a system with around 330 databases running PostgreSQL 8.4.2

What would the expected behavior be with AutoVacuum_NapTime set to the
default of 1m and autovacuum_workers set to 3?

What I'm observing is that the system is continuously vacuuming databases.
Would these settings mean the autovacuum worker would try to vacuum all 330
databases once per minute?

George Sexton


From:
Tom Lane
Date:

"George Sexton" <> writes:
> I have a system with around 330 databases running PostgreSQL 8.4.2
> What would the expected behavior be with AutoVacuum_NapTime set to the
> default of 1m and autovacuum_workers set to 3?

autovacuum_naptime is the cycle time for any one database, so you'd
get an autovac worker launched every 60/330 seconds ...

            regards, tom lane

From:
"George Sexton"
Date:

> -----Original Message-----
> From: Tom Lane [mailto:]
> Sent: Saturday, February 20, 2010 6:15 PM
> To: George Sexton
> Cc: 
> Subject: Re: [PERFORM] AutoVacuum_NapTime
>
> "George Sexton" <> writes:
> > I have a system with around 330 databases running PostgreSQL 8.4.2
> > What would the expected behavior be with AutoVacuum_NapTime set to
> the
> > default of 1m and autovacuum_workers set to 3?
>
> autovacuum_naptime is the cycle time for any one database, so you'd
> get an autovac worker launched every 60/330 seconds ...
>
>             regards, tom lane

Thanks. That's non-optimal for my usage. I'll change it.

Another question then. Say I set it to 720 minutes, which if I understand
things would see each db done twice per day.

If I'm cold starting the system, would it vacuum all 330 databases and then
wait 720 minutes and then do them all again, or would it distribute the
databases more or less evenly over the time period?

George Sexton
MH Software, Inc.
http://www.mhsoftware.com/
Voice: 303 438 9585


From:
Alvaro Herrera
Date:

George Sexton wrote:

> If I'm cold starting the system, would it vacuum all 330 databases and then
> wait 720 minutes and then do them all again, or would it distribute the
> databases more or less evenly over the time period?

the latter

--
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.