Re: Note new NULLS NOT DISTINCT on unique index tutorial page

David Rowley <dgrowleyml@gmail.com>

From: David Rowley <dgrowleyml@gmail.com>
To: Corey Huinker <corey.huinker@gmail.com>
Cc: David Gilman <davidgilman1@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-04-18T03:22:36Z
Lists: pgsql-hackers
On Tue, 18 Apr 2023 at 05:01, Corey Huinker <corey.huinker@gmail.com> wrote:
> I'm ok with the wording as-is, but perhaps we can phrase it as "distinct" vs "not equal", thus leaning into the syntax a bit:
>
> By default, null values in a unique column are considered distinct, allowing multiple nulls in the column.
>
>
> or maybe
>
> By default, null values in a unique column are considered <literal>DISTINCT</literal>, allowing multiple nulls in the column.>

I acknowledge your input, but I didn't think either of these was an
improvement over what David suggested.  I understand that many people
will know that "SELECT DISTINCT" and "WHERE x IS NOT DISTINCT FROM y"
means treat NULLs equally, but I don't think we should expect the
reader here to know that's what we're talking about.   In any case,
we're talking about existing wording here, not something David is
adding.

David



Commits

  1. Doc: clarify NULLS NOT DISTINCT use in unique indexes