From: | David Pratt <fairwinds(at)eastlink(dot)ca> |
---|---|
To: | Bruno Wolff III <bruno(at)wolff(dot)to> |
Cc: | pgsql-admin(at)postgresql(dot)org |
Subject: | Re: Adding Serial Type |
Date: | 2005-05-28 19:18:30 |
Message-ID: | 46D712FF-CFAD-11D9-AEE7-000A27B3B070@eastlink.ca |
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Thread: | |
Lists: | pgsql-admin |
On Saturday, May 28, 2005, at 03:27 PM, Bruno Wolff III wrote:
> On Sat, May 28, 2005 at 14:27:17 -0300,
> David Pratt <fairwinds(at)eastlink(dot)ca> wrote:
>> Pretty basic question. Is it necessary to add NOT NULL or UNIQUE NOT
>> NULL to SERIAL or is this implicit and unnecessary?
>
> Serials no longer generate a uniqie index by default. So in practice
> you will normally want to declare them as PRIMARY KEYs. However there
> are cases where you don't need this and the index is extra overhead.
>
Alright. so would it be better form for me to to this in a
create_tables.sql
CREATE TABLE new_table (
id SERIAL,
description TEXT NOT NULL
);
And then in a create_primary_keys.sql do this for the tables requiring
it.
ALTER TABLE new_table ADD CONSTRAINT new_table_pkey PRIMARY KEY (id);
Does the PRIMARY KEY declaration ensure that the id values are unique?
Serial should always give me an incremented value that's different so I
am assuming it is unnecessary to use UNIQUE. Am I correct?
Regards,
David
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