Re: index unique

On 2021-06-07 10:20:22 -0700, David G. Johnston wrote:
> On Sun, Jun 6, 2021 at 11:55 PM Peter J. Holzer <hjp-pgsql(at)hjp(dot)at> wrote:
> On 2021-06-03 22:51:55 +0200, Marc Millas wrote:
> > postgres 12 with postgis.
> > on a table we need a primary key and to get a unique combinaison, we need
> > 3 columns of that table:
> > 1 of type integer,
> > 1 of type text,
> > 1 of type geometry
> >
> > creating the PK constraint doesn work:
>
> I find that if a natural primary key candidate is so complex, it is
> usually better to use a surrogate key.
>
>
> You make this sound like an either-or proposition,

While he is talking about *a* primary key, it should be *the* primary
key. There can be only one (that's why it is the primary key).

There can be several unique keys, though.

> but personally it takes a very exceptional circumstance to forgo
> defining a unique natural key.

True, but not what he's talking about.

hp

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_ | Peter J. Holzer | Story must make more sense than reality.
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