Re: Rules of Thumb for Autovaccum

On Wed, Feb 15, 2012 at 09:14:34AM -0500, Robert James wrote:
> What rules of thumb exist for:
> * How often a table needs to be vacuumed?
> * How often a table needs to be analyzed?
> * How to tune Autovacuum?
>
> I have a large DB server, and I'm concerned that it's not being
> autovaccumed and autoanalyzed frequently enough.  But I have no idea
> what proper values should be?
>
> A related question: If I INSERT a large number of records per day,
> similar in nature to the existing records, does that require new
> vacuum? new analyze? Or do I only need those for DELETEs or changes to
> the nature of records?
>
> Finally: What type of performance impact can I expect from vacuum and
> analyze, in general?

Unless you are very high-volume, the auto-vacuum default settings are
fine.  The default do allow up to 20% of unused space in tables, but
making that lower is expensive to performance.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +