--source include/have_debug_sync.inc

create table t (a int);

insert into t values (1),(2);

--send

  set debug_sync= 'now wait_for downgraded';

--connect (con_alter,localhost,root,,test)

set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for goforit';

--send

  alter table t add check (a<10), algorithm=copy, lock=none;

--connection default

--reap

insert into t values (11),(12);

set debug_sync= 'now signal goforit';

--connection con_alter

--reap

show create table t;

select * from t;

# Cleanup

drop table t;

set debug_sync= reset;

connection con_alter;

show create table t;

Table	Create Table

t	CREATE TABLE `t` (

  `a` int(11) DEFAULT NULL,

  CONSTRAINT `CONSTRAINT_1` CHECK (`a` < 10)

) ENGINE=MyISAM DEFAULT CHARSET=latin1

select * from t;

a

1

2

11

12