connect  con1,localhost,root,,;
connect  con2,localhost,root,,;
connection default;
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;
connection con2;
SET DEBUG_SYNC='row_log_apply_before SIGNAL created_u WAIT_FOR dml_done_u';
ALTER TABLE u ADD INDEX (c);
connection default;
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
connection con1;
SET DEBUG_SYNC='row_log_apply_before SIGNAL created_t WAIT_FOR dml_done_t';
CREATE INDEX c1 ON t (c(1));
connection default;
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';
connection con2;
SET DEBUG_SYNC='now SIGNAL dml_done_t';
disconnect con2;
connection con1;
disconnect con1;
connection default;
SET DEBUG_SYNC='RESET';
DROP TABLE t,u;