| From: | Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Statistics "dependency" |
| Date: | 2017-04-23 08:17:09 |
| Message-ID: | CAEZATCX9Azy2PTU70c84v75YQW7Gu_kwaubGZwJFiJfLJSoZuA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 23 April 2017 at 03:37, Bruce Momjian <bruce(at)momjian(dot)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
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