Re: stable and immutable functions in GROUP BY clauses.

>
> Hello,
>
> Stable and immutable functions do not improve performance when used within the GROUP BY clause.
> Here, the function will be called for each row.
>
> To avoid it, I can replace the funtion by its arguments within GROUP BY.

Shame on me !
This is of course bullsh...  It has nothing to do with immutability and can only applies to few cases

e.g: it's fine for select x+1 ... group by  x,
but not for        select x^2 ... group by  x

Marc Mamin