CREATE TABLE t1 (id INT PRIMARY KEY) ENGINE=InnoDB;
INSERT INTO t1 VALUES (1);
ALTER TABLE t1 ADD COLUMN f2 INTEGER, LOCK=SHARED;
INSERT INTO t1 VALUES (2, 2);
SELECT COUNT(*) = 2 FROM t1;
COUNT(*) = 2
1
INSERT INTO t1 VALUES (3, 3);
SELECT COUNT(*) = 3 FROM t1;
COUNT(*) = 3
1
DROP TABLE t1;