MySQL Sequence Emulation (Licensed under CC0)

demo.sql

INSERT INTO sequence values('one', 100);
INSERT INTO sequence values('two', 1000);

SELECT sequence('one');
SELECT sequence('two');
SELECT sequence('one');
SELECT sequence('one');
SELECT sequence('two');

performance.md

sequence_insert() * 10000

real    0m0.946s
user    0m0.082s
sys     0m0.064s

sequence_update() * 10000

real    0m1.111s
user    0m0.069s
sys     0m0.071s

setup.sql

CREATE TABLE sequence (
	name VARCHAR(20) NOT NULL PRIMARY KEY,
	value INT unsigned NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

delimiter //
CREATE FUNCTION sequence_update(seq_name VARCHAR(20))
	RETURNS INT
BEGIN
	UPDATE sequence SET value=LAST_INSERT_ID(value+1) WHERE name=seq_name;
	RETURN LAST_INSERT_ID();
END
//
delimiter ;

delimiter //
CREATE FUNCTION sequence_insert(seq_name VARCHAR(20))
	RETURNS INT
BEGIN
	INSERT INTO sequence (name, value) VALUES (seq_name, LAST_INSERT_ID(1))
		ON DUPLICATE KEY UPDATE value=LAST_INSERT_ID(value+1);
	RETURN LAST_INSERT_ID();
END
//
delimiter ;