connection node_2;
connection node_1;
#
# MDEV#5552 Deadlock when inserting NULL column value in column with
# UNIQUE index
#
USE test;

# On node_1
connection node_1;
CREATE TABLE t1(c1 INT DEFAULT NULL, UNIQUE KEY c1(c1)) ENGINE=INNODB;
INSERT INTO t1 VALUES (NULL);
INSERT INTO t1 VALUES (NULL);
SELECT * FROM test.t1;
c1
NULL
NULL

# On node_2
connection node_2;
SELECT * FROM test.t1;
c1
NULL
NULL

# On node_1
connection node_1;
INSERT INTO t1 VALUES (1);
UPDATE t1 SET c1=NULL WHERE c1=1;
SELECT * FROM test.t1;
c1
NULL
NULL
NULL

# On node_2
connection node_2;
SELECT * FROM test.t1;
c1
NULL
NULL
NULL

# On node_1
connection node_1;
DELETE FROM t1 WHERE c1<=>NULL;
SELECT * FROM test.t1;
c1

# On node_2
connection node_2;
SELECT * FROM test.t1;
c1
DROP TABLE t1;
disconnect node_2;
disconnect node_1;
# End of test