Re: Improving N-Distinct estimation by ANALYZE

Greg,

> These numbers don't make much sense to me. It seems like 5% is about as
> slow as reading the whole file which is even worse than I expected. I
> thought I was being a bit pessimistic to think reading 5% would be as
> slow as reading 20% of the table.

It's about what *I* expected.  Disk seeking is the bane of many access 
methods.

Anyway, since the proof is in the pudding, Simon and I will be working on 
some demo code for different sampling methods so that we can debate 
results rather than theory.

-- 
--Josh

Josh Berkus
Aglio Database Solutions
San Francisco