Re: estimating # of distinct values

On Jan 17, 2011, at 6:36 PM, Tomas Vondra wrote:
> 1) Forks are 'per relation' but the distinct estimators are 'per
>   column' (or 'per group of columns') so I'm not sure whether the file
>   should contain all the estimators for the table, or if there should
>   be one fork for each estimator. The former is a bit difficult to
>   manage, the latter somehow breaks the current fork naming convention.

Yeah, when I looked at the fork stuff I was disappointed to find out there's essentially no support for dynamically
addingforks. There's two other possible uses for that I can think of: 

- Forks are very possibly a more efficient way to deal with TOAST than having separate tables. There's a fair amount of
overheadwe pay for the current setup. 
- Dynamic forks would make it possible to do a column-store database, or at least something approximating one.

Without some research, there's no way to know if either of the above makes sense; but without dynamic forks we're
prettymuch dead in the water. 

So I wonder what it would take to support dynamically adding forks...
--
Jim C. Nasby, Database Architect                   jim@nasby.net
512.569.9461 (cell)                         http://jim.nasby.net