DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (pk INT PRIMARY KEY, a INT AUTO_INCREMENT, KEY(a)) ENGINE=xengine;
INSERT INTO t1 (pk) VALUES (3), (2), (1);
SELECT * FROM t1;
pk	a
3	1
2	2
1	3
# restart
INSERT INTO t1 (pk) VALUES (4);
SELECT * FROM t1;
pk	a
3	1
2	2
1	3
4	4
DROP TABLE t1;