Re: Autovacuum on by default?

On Thu, Aug 17, 2006 at 01:47:37PM -0400, Matthew T. O'Connor wrote:
> Alvaro Herrera wrote:
> >Matthew T. O'Connor wrote:
> >  
> >>I assume you are suggesting that the base value be 0?  Well for one 
> >>thing if the table doesn't have any rows that will result in constant 
> >>vacuuming of that table, so it needs to be greater than 0.  For a small 
> >>table, say 100 rows, there usually isn'tn much performance impact if the 
> >>table if 50% dead space, so I think the base values you suggest are OK, 
> >>but they shouldn't be 0.
> >>    
> >
> >Actually Tom suggested some time ago that we should get rid of the base
> >value completely, i.e. make it 0 forever.
> >
> >A row with 0 tables would not show any activity in pgstats, so it would
> >not be vacuumed constantly.  Only once after it's truncated.
> 
> OK, forgot that.  Well I put it in originally as a way to give more 
> flexability to the calculation, if I want a tabled vacuumed every 100 
> updates, then I can set the scaling factor to 0 and the base value to 
> 100, but maybe that's not really needed.  It would simplify things if we 
> got rid of it.

I think it makes more sense in the per-table settings (which I can't
remember if we actually have yet). For example, on a frequently update
table that you know should always be small, you might well want to set
it to scaling factor 0 and base of 20 or whatever.
-- 
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