| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Geoff Winkless <pgsqladmin(at)geoff(dot)dj> |
| Cc: | "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Is PRIMARY KEY the same as UNIQUE NOT NULL? |
| Date: | 2016-02-07 21:04:35 |
| Message-ID: | 25592.1454879075@sss.pgh.pa.us |
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| Thread: | |
| Lists: | pgsql-general |
Geoff Winkless <pgsqladmin(at)geoff(dot)dj> writes:
> On 31 January 2016 at 19:53, David G. Johnston
> <david(dot)g(dot)johnston(at)gmail(dot)com> wrote:
>> A PRIMARY KEY enforces a UNIQUE, NOT NULL constraint and additionally allows
> [snip]
> I would just remove the whole paragraph. A primary key does what it
> does, a unique constraint does what it does. I'm not really sure why
> you need to link them.
I think it is useful to compare them; the only problem is claiming that
they're equivalent.
I've applied some doc updates based on this discussion.
regards, tom lane
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