Re: BUG #14121: Constraint UNIQUE - Mailing list pgsql-bugs

On Thu, May 5, 2016 at 5:46 AM, Marco Giraldo <m.giraldo@stt-telefonia.it>
wrote:

> Hi John
>
> Excuse me for the late but I have many work problem.
>

=E2=80=8BI understand.


> I hope I understand what you mean.
>
> But I do this constraint CREATE TABLE (pippo date UNIQUE, pluto date) etc=
=E2=80=A6
>
> And I don=E2=80=99t can remove this restriction.
>

=E2=80=8BCan you show me (and the entire pg=E2=80=8Bsql-bugs group also) wh=
at happens when
you try? That is, in psql, enter something like:

CREATE TABLE name (pippo date UNIQUE, pluto date);
\d+ name

What does the \d+ output show?

This is what happens when I do this:

[tsh009@it-johnmckown-linux syslog]$ psql
psql (9.4.7)
Type "help" for help.

tsh009@tsh009=3D# CREATE TABLE name (pippo date UNIQUE, pluto date);
CREATE TABLE
tsh009@tsh009=3D# \d+ name
                       Table "public.name"
 Column | Type | Modifiers | Storage | Stats target | Description
--------+------+-----------+---------+--------------+-------------
 pippo  | date |           | plain   |              |
 pluto  | date |           | plain   |              |
Indexes:
    "name_pippo_key" UNIQUE CONSTRAINT, btree (pippo)

tsh009@tsh009=3D# insert into name(pippo,pluto)
values('2016-01-01'::date,'2016-01-02'::date);
INSERT 0 1
type=3DSTREAM tsh009@tsh009=3D# select * from name;
   pippo    |   pluto
------------+------------
 2016-01-01 | 2016-01-02
(1 row)

tsh009@tsh009=3D# insert into name(pippo,pluto)
values('2016-01-01'::date,'2016-01-03'::date);
ERROR:  duplicate key value violates unique constraint "name_pippo_key"
DETAIL:  Key (pippo)=3D(2016-01-01) already exists.
tsh009@tsh009=3D# ALTER TABLE name DROP CONSTRAINT name_pippo_key;
ALTER TABLE
tsh009@tsh009=3D# \d+ name
                       Table "public.name"
 Column | Type | Modifiers | Storage | Stats target | Description
--------+------+-----------+---------+--------------+-------------
 pippo  | date |           | plain   |              |
 pluto  | date |           | plain   |              |

tsh009@tsh009=3D# insert into name(pippo,pluto)
values('2016-01-01'::date,'2016-01-03'::date);
INSERT 0 1
tsh009@tsh009=3D#


=E2=80=8BThe first INSERT works because the table is empty. The second time=
, the
INSERT fails because of the duplicate key. But after the ALTER TABLE ...
DROP CONSTRAINT, I can do the second INSERT again and it succeeds.=E2=80=8B



>
>
>
>
> *Da:* John McKown [mailto:john.archie.mckown@gmail.com]
> *Inviato:* venerd=C3=AC 29 aprile 2016 16:47
> *A:* Marco Giraldo <m.giraldo@stt-telefonia.it>
> *Cc:* pgsql-bugs@postgresql.org
> *Oggetto:* Re: [BUGS] BUG #14121: Constraint UNIQUE
>
>
>
> On Fri, Apr 29, 2016 at 5:35 AM, <m.giraldo@stt-telefonia.it> wrote:
>
> The following bug has been logged on the website:
>
> Bug reference:      14121
> Logged by:          Marco
> Email address:      m.giraldo@stt-telefonia.it
> PostgreSQL version: 9.5.0
> Operating system:   Windows 7
> Description:
>
> Hi
> I have a problem with UNIQUE constraint.
> I don't understand the difference from TYPE type UNIQUE(when I declare a
> column of the table) and ALTER TABLE table ADD CONSTRAINT column UNIQUE
> (column).
> How can I remove the UNIQUE option from TYPE declaration?
>
> Best reguards
>
>
>
> =E2=80=8BALTER TABLE table DROP CONSTRAINT constraint_name;
>
>
>
> Example:
>
>
>
> # create table c(c text unique);
>
>
>
> CREATE TABLE
>
>
>
> # \d+ c
>
>                          Table "public.c"
>
>
>
>  Column | Type | Modifiers | Storage  | Stats target | Description
>
>
>
> --------+------+-----------+----------+--------------+-------------
>
>
>
>  c      | text |           | extended |              |
>
>
>
> Indexes:
>
>
>
>     "c_c_key" UNIQUE CONSTRAINT, btree (c)
>
>
>
>
>
>
>
>
>
> # alter table c drop constraint c_c_key;
>
> ALTER TABLE
>
> # \d+ c
>
>                          Table "public.c"
>
>  Column | Type | Modifiers | Storage  | Stats target | Description
>
> --------+------+-----------+----------+--------------+-------------
>
>  c      | text |           | extended |              |
>
> =E2=80=8B
>
>
>
>
>
>
> --
>
> The unfacts, did we have them, are too imprecisely few to warrant our
> certitude.
>
>
>
> Maranatha! <><
> John McKown
>
> ------------------------------
>
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>



--=20
The unfacts, did we have them, are too imprecisely few to warrant our
certitude.

Maranatha! <><
John McKown