Re: Question about VACUUM

Josh Berkus <josh@agliodbs.com> wrote:
> On 12/5/11 1:36 PM, Kevin Grittner wrote:
>> I understand the impulse to run autovacuum less frequently or
>> less aggressively.  When we first started running PostgreSQL the
>> default configuration was very cautious.
>
> The default settings are deliberately cautious, as default
> settings should be.

I was talking historically, about the defaults in 8.1:

http://www.postgresql.org/docs/8.1/interactive/runtime-config-autovacuum.html

Those defaults were *over*-cautious to the point that we experienced
serious problems.  My point was that many people's first instinct in
that case is to make the setting less aggressive, as I initially did
and the OP has done.  The problem is actually solved by making them
*more* aggressive.  Current defaults are pretty close to what we
found, through experimentation, worked well for us for most
databases.

> But yes, anyone with a really large/high-traffic database will
> often want to make autovac more aggressive.

I think we're in agreement: current defaults are good for a typical
environment; high-end setups still need to tune to more aggressive
settings.  This is an area where incremental changes with monitoring
works well.

-Kevin