RESET MASTER;
connection default;
# MERGE is the only remaning non-specialized SE (like NDB or P_S)
# which implements TRUNCATE TABLE through handler::truncate().
CREATE TABLE t0(id INT AUTO_INCREMENT PRIMARY KEY, a INT, b INT) ENGINE=MyISAM;
CREATE TABLE t1(id INT AUTO_INCREMENT PRIMARY KEY, a INT, b INT) ENGINE=MERGE UNION=(t0) INSERT_METHOD=LAST;
INSERT INTO t1(a, b) VALUES(1,2),(2,4),(3,6),(4,8),(5,10);
SET DEBUG_SYNC = "open_and_process_table signal truncate_before_lock wait_for forever";
TRUNCATE t1;
connect con1,localhost,root,,;
SET DEBUG_SYNC = "now wait_for truncate_before_lock";
SELECT ((@id := id) - id) FROM information_schema.processlist WHERE processlist.info LIKE '%TRUNCATE t1%' AND state LIKE '%open_and_process_table%';
((@id := id) - id)
0
Warnings:
Warning	1287	Setting user variables within expressions is deprecated and will be removed in a future release. Consider alternatives: 'SET variable=expression, ...', or 'SELECT expression(s) INTO variables(s)'.
KILL QUERY @id;
connection default;
ERROR 70100: Query execution was interrupted
connection con1;
include/show_binlog_events.inc
connection con1;
connection con1;
Log_name	Pos	Event_type	Server_id	End_log_pos	Info
binlog.000001	#	Query	#	#	use `test`; CREATE TABLE t0(id INT AUTO_INCREMENT PRIMARY KEY, a INT, b INT) ENGINE=MyISAM
binlog.000001	#	Query	#	#	use `test`; CREATE TABLE t1(id INT AUTO_INCREMENT PRIMARY KEY, a INT, b INT) ENGINE=MERGE UNION=(t0) INSERT_METHOD=LAST
binlog.000001	#	Query	#	#	BEGIN
binlog.000001	#	Intvar	#	#	INSERT_ID=1
binlog.000001	#	Query	#	#	use `test`; INSERT INTO t1(a, b) VALUES(1,2),(2,4),(3,6),(4,8),(5,10)
binlog.000001	#	Query	#	#	COMMIT
connection con1;
connection con1;
disconnect con1;
connection default;
SELECT * FROM t1;
id	a	b
1	1	2
2	2	4
3	3	6
4	4	8
5	5	10
DROP TABLE t1, t0;
SET DEBUG_SYNC= 'RESET';