From: | Ben Leslie <benno(at)benno(dot)id(dot)au> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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 22:45:22 |
Message-ID: | CABZ0LtBPbD6uWDvMOQNYyF=29NJefewHAwGfsh1iark2wHhZHw@mail.gmail.com |
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Lists: | pgsql-general |
On 8 February 2016 at 08:04, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> 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.
>
> http://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=c477e84fe2471cb675234fce75cd6bb4bc2cf481
>
> regards, tom lane
Thanks Tom,
I think with the documentation expressed this way I don't think I
would have made the error I did originally; from my point of view it
is a welcome improvement.
Cheers,
Ben
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