Re: Autovacuum on by default?

On Wed, Aug 23, 2006 at 01:45:43PM +0900, ITAGAKI Takahiro wrote:
> 
> "Jim C. Nasby" <jnasby@pervasive.com> wrote:
> 
> > And +1 on Rod's suggestion to make it more aggressive. I always drop the
> > scale factor to at least 0.2 and 0.1 (though 0.1 and 0.05 don't seem
> > unreasonable), and typically drop the thresholds to 200 and 100 (though
> > again, lower is probably warrented).
> 
> The default fillfactors for index btree is 90%. So if we want to avoid
> spliting of the leaf pages, vacuum scale factors should be less than 0.1
> in cases where tuples are only updated randomly. I think threshoulds should
> be less than PCTFREEs(=1-fillfactors) except ever-increasing tables.

Very good point, though at least for indexes the new code that tries to
reclaim space on a page before splitting it will help. Doesn't help for
the heap, though.

So maybe the default should be 0.08?
-- 
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461