drop table if exists t1;
CREATE TABLE t1(
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
k INT,
c CHAR(1),
UNIQUE KEY(k)) ENGINE=InnoDB;
#
# Connection 1
#
SET DEBUG_SYNC='ha_write_row_end SIGNAL continue2 WAIT_FOR continue1';
affected rows: 0
INSERT INTO t1(k) VALUES (1), (2), (3) ON DUPLICATE KEY UPDATE c='1';
#
# Connection 2
#
SET DEBUG_SYNC='ha_write_row_start WAIT_FOR continue2';
affected rows: 0
SET DEBUG_SYNC='after_mysql_insert SIGNAL continue1';
affected rows: 0
INSERT INTO t1(k) VALUES (2), (4), (5) ON DUPLICATE KEY UPDATE c='2';
affected rows: 3
info: Records: 3  Duplicates: 0  Warnings: 0
affected rows: 4
info: Records: 3  Duplicates: 1  Warnings: 0
SET DEBUG_SYNC='RESET';
SELECT * FROM t1 ORDER BY k;
id	k	c
1	1	NULL
4	2	1
2	3	NULL
5	4	NULL
6	5	NULL
DROP TABLE t1;