CREATE TABLE t (a INT PRIMARY KEY, c TEXT) ENGINE=InnoDB; CREATE TABLE u (a INT PRIMARY KEY, b INT, c INT NOT NULL) ENGINE=InnoDB; INSERT INTO t VALUES (1,'aa'); BEGIN; INSERT INTO u SET a=1, c=1; INSERT INTO u SELECT a+1,NULL,a+1 FROM u; INSERT INTO u SELECT a+2,NULL,a+2 FROM u; INSERT INTO u SELECT a+4,NULL,a+4 FROM u; INSERT INTO u SELECT a+8,NULL,a+8 FROM u; INSERT INTO u SELECT a+16,NULL,a+16 FROM u; INSERT INTO u SELECT a+32,NULL,a+32 FROM u; INSERT INTO u SELECT a+64,NULL,a+64 FROM u; INSERT INTO u SELECT a+128,NULL,a+64 FROM u; INSERT INTO u SELECT a+256,NULL,a+64 FROM u; COMMIT; BEGIN; DELETE FROM u; SET DEBUG_SYNC='row_log_apply_before SIGNAL created_u WAIT_FOR dml_done_u'; ALTER TABLE u ADD INDEX (c); COMMIT; SET DEBUG_SYNC='now WAIT_FOR created_u'; SELECT state FROM information_schema.processlist WHERE info='ALTER TABLE u ADD INDEX (c)'; state debug sync point: row_log_apply_before SET DEBUG_SYNC='row_log_apply_before SIGNAL created_t WAIT_FOR dml_done_t'; CREATE INDEX c1 ON t (c(1)); SET DEBUG_SYNC='now WAIT_FOR created_t'; UPDATE t SET c='ab'; SELECT SLEEP(10); SLEEP(10) 0 SET DEBUG_SYNC='now SIGNAL dml_done_u'; SET DEBUG_SYNC='now SIGNAL dml_done_t'; SET DEBUG_SYNC='RESET'; DROP TABLE t,u;