Re: Potential autovacuum optimization: new tables

On Sat, Oct 13, 2012 at 12:49 PM, Joshua Berkus <josh@agliodbs.com> wrote:
>
> So, problem #1 is coming up with a mathematical formula.  My initial target values are in terms of # of rows in the
tablevs. # of writes before analyze is triggered:
 
>
> 1 : 3
> 10 : 5
> 100 : 10
> 1000 : 100
> 100000 : 2000
> 1000000 : 5000
> 10000000 : 25000
> 100000000 : 100000
>
> .... etc.  So problem #1 is a mathematical formula which gives this kind of curve.  I've tried some solution-seeking
software,but I don't know how to use it well enough to get something useful.
 

That is close to a power law, where best fit is about "threshold = 1.5
* (rows ** 0.6)"

rows      yours     powerfit
1.00E+00    3.00E+00    1.50E+00
1.00E+01    5.00E+00    5.97E+00
1.00E+02    1.00E+01    2.38E+01
1.00E+03    1.00E+02    9.46E+01
1.00E+05    2.00E+03    1.50E+03
1.00E+06    5.00E+03    5.97E+03
1.00E+07    2.50E+04    2.38E+04
1.00E+08    1.00E+05    9.46E+04

If you want something more natural, reduce the exponent from 0.6 to
0.5 so it becomes the square root.

I have no opinion on the suitability of this, I'm just crunching the
numbers for you.

Cheers,

Jeff