DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a INT, b CHAR(8), pk INT AUTO_INCREMENT PRIMARY KEY) ENGINE=xengine;
REPLACE INTO t1 (a,b) VALUES (1,'a'),(2,'b'),(3,'c'),(4,'d'),(5,'e');
SELECT a,b FROM t1;
a	b
1	a
2	b
3	c
4	d
5	e
REPLACE t1 (a,b) VALUE (10,'foo'),(10,'foo');
SELECT a,b FROM t1;
a	b
1	a
10	foo
10	foo
2	b
3	c
4	d
5	e
DROP TABLE t1;
CREATE TABLE t1 (a INT, b CHAR(8), PRIMARY KEY (b)) ENGINE=xengine;
REPLACE INTO t1 (a,b) VALUES (1,'a'),(2,'b'),(3,'c');
INSERT INTO t1 (a,b) VALUES (4,'b');
ERROR 23000: Duplicate entry 'b' for key 'PRIMARY'
REPLACE INTO t1 (a,b) VALUES (4,'b');
SELECT a,b FROM t1;
a	b
1	a
3	c
4	b
DROP TABLE t1;