create database a; use a; create table t1(a int); insert into t1 values(1); create table t2(a int); insert into t2 values(1); create database b; use b; create table t1(a int); insert into t1 values(1); create table t2(a int); insert into t2 values(1); create database c; use c; create table t1(a int); insert into t1 values(1); create table t2(a int); insert into t2 values(1); change master 'm1' to master_port=MYPORT_1 , master_host='127.0.0.1', master_user='root'; change master 'm2' to master_port=MYPORT_2 , master_host='127.0.0.1', master_user='root'; change master to master_port=MYPORT_3 , master_host='127.0.0.1', master_user='root'; start all slaves; set default_master_connection = 'm1'; include/wait_for_slave_to_start.inc set default_master_connection = 'm2'; include/wait_for_slave_to_start.inc set default_master_connection = ''; include/wait_for_slave_to_start.inc use a; show tables; Tables_in_a t1 t2 use b; show tables; Tables_in_b t1 t2 use c; show tables; Tables_in_c t1 t2 #TEST SET default_master_connection = "m1"; SET default_master_connection = "m2"; SET default_master_connection = ""; flush logs; SET default_master_connection = "m1"; #log Rotated mysqld-relay-bin.000002 mysqld-relay-bin.000003 mysqld-relay-bin.index SET default_master_connection = "m2"; #log Rotated mysqld-relay-bin-m1.000002 mysqld-relay-bin-m1.000003 mysqld-relay-bin-m1.index SET default_master_connection = ""; #log Rotated mysqld-relay-bin-m2.000002 mysqld-relay-bin-m2.000003 mysqld-relay-bin-m2.index #CleanUp drop database a; drop database b; drop database c; stop all slaves; Warnings: Note 1938 SLAVE 'm2' stopped Note 1938 SLAVE '' stopped Note 1938 SLAVE 'm1' stopped SET default_master_connection = "m1"; include/wait_for_slave_to_stop.inc SET default_master_connection = "m2"; include/wait_for_slave_to_stop.inc SET default_master_connection = ""; include/wait_for_slave_to_stop.inc