CREATE TABLE t1 (a INT, b INT AS (a), KEY(b)) ENGINE=InnoDB;
INSERT INTO t1 () VALUES (),();
connect  con1,localhost,root,,test;
ALTER TABLE t1 ADD COLUMN x INT as (a), add key(x), ALGORITHM=COPY;
SET debug_sync= "ib_open_after_dict_open SIGNAL delete_open WAIT_FOR another_open";
DELETE FROM t1;
connection default;
SET debug_sync= "now WAIT_FOR delete_open";
SELECT a FROM t1;
a
NULL
NULL
SET debug_sync= "now SIGNAL another_open";
connection con1;
disconnect con1;
connection default;
SET debug_sync= "RESET";
DROP TABLE t1;