Reply-To: <ries@jongert.nl>
From: "Ries van Twisk" <ries@jongert.nl>
To: <pgsql-sql@postgresql.org>
Subject: Dublicates pairs in a table.
Date: Mon, 16 Sep 2002 16:51:23 +0200
Message-ID: <000201c25d90$87230c10$6500000a@IT000>
MIME-Version: 1.0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Importance: Normal

Dear guys/girls,

I have a small question which I could not clearly find in the postgreSQL
manual.

if I create this table and index
CRAEATE TABLE test (
	id	SERIAL,
	c1	VARCHAR(32),
	c2	VARCHAR(32),
	c3	VARCHAR(32)
);

CREATE UNIQUE INDEX test_idx ON test(id, c1,c2);

what I try to archive here is that I don't want duplicate pais in my table:
example

INSET INTO test (c1,c2) VALUES('a', 'a');	-- Allowed
INSET INTO test (c1,c2) VALUES('b', 'b');	-- Allowed
INSET INTO test (c1,c2) VALUES('b', 'c');	-- Allowed
INSET INTO test (c1,c2) VALUES('a', 'a');	-- Not allowed since we already
have a duplicate ('a', 'a') pair
INSET INTO test (c1,c2) VALUES('b', 'c');	-- Not allowed since we already
have a duplicate ('b', 'c') pair

etc. etc. I think you get the idea...

What I want to know is that if this is smart do do, or is there a other
better way to make sure I don't insert duplicate pairs in my database.
I'm not sure if a stored procedure is better in my case since I don't really
need the index on columns c1 or c2.
I'm looking for performance technical answers here thus speed vs memory
comparisons. Ofcourse a pointer to a URL will also do..

Best Regards,
Ries van Twisk