Re: [HACKERS] Statistics "dependency"

On 23 April 2017 at 03:37, Bruce Momjian <bruce@momjian.us> wrote:
> In looking at the new multi-column statistics "dependency" option in
> Postgres 10, I am quite confused by the term "dependency".  Wouldn't
> "correlation" be clearer and less confusing as "column dependency"
> already means something else.
>

Actually, the terms "dependency" and "correlation" are both quite
broad terms that cover a whole range of other different things, and
hence could be misleading. The precise term for this is "functional
dependency" [1], so if anything, the option name should be
"functional_dependencies" or some shortening of that, keeping a part
of each of those words.

Regards,
Dean

[1] https://en.wikipedia.org/wiki/Functional_dependency