Re: PRIMARY KEY on a *group* of columns imply that each column is NOT

From: Stephane Bortzmeyer <bortzmeyer(at)nic(dot)fr>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Stephane Bortzmeyer <bortzmeyer(at)nic(dot)fr>, Scott Marlowe <smarlowe(at)g2switchworks(dot)com>, Guy Rouillier <guyr(at)masergy(dot)com>, pgsql-general(at)postgresql(dot)org
Subject: Re: PRIMARY KEY on a *group* of columns imply that each column is NOT
Date: 2005-04-27 14:36:49
Message-ID: 20050427143649.GA848@nic.fr
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On Wed, Apr 27, 2005 at 10:26:30AM -0400,
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote
a message of 9 lines which said:

> If that's what you want, declare it as UNIQUE not PRIMARY KEY.

As shown by Patrick TJ McPhee, it does not work:

tests=> create table x (
tests(> name TEXT NOT NULL,
tests(> address INET,
tests(> CONSTRAINT na UNIQUE (name, address)
tests(> );
NOTICE: CREATE TABLE / UNIQUE will create implicit index "na" for table "x"
CREATE TABLE
tests=> INSERT INTO x (name) values ('foobar');
INSERT 45380 1
tests=> INSERT INTO x (name) values ('foobar');
INSERT 45381 1
tests=> INSERT INTO x (name) values ('foobar');
INSERT 45382 1
tests=> INSERT INTO x (name) values ('foobar');
INSERT 45383 1
tests=> select * from x;
name | address
--------+---------
foobar |
foobar |
foobar |
foobar |
(4 rows)

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