INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so'; select @@global.rpl_semi_sync_master_timeout; @@global.rpl_semi_sync_master_timeout 10000 SET @start_global_value = @@global.rpl_semi_sync_master_timeout; Assuming value will not be more then 100 sec select @@global.rpl_semi_sync_master_timeout between 1 and 100000; @@global.rpl_semi_sync_master_timeout between 1 and 100000 1 select @@session.rpl_semi_sync_master_timeout; ERROR HY000: Variable 'rpl_semi_sync_master_timeout' is a GLOBAL variable show global variables like 'rpl_semi_sync_master_timeout'; Variable_name Value rpl_semi_sync_master_timeout 10000 show session variables like 'rpl_semi_sync_master_timeout'; Variable_name Value rpl_semi_sync_master_timeout 10000 select * from information_schema.global_variables where variable_name='rpl_semi_sync_master_timeout'; VARIABLE_NAME VARIABLE_VALUE RPL_SEMI_SYNC_MASTER_TIMEOUT 10000 select * from information_schema.session_variables where variable_name='rpl_semi_sync_master_timeout'; VARIABLE_NAME VARIABLE_VALUE RPL_SEMI_SYNC_MASTER_TIMEOUT 10000 set global rpl_semi_sync_master_timeout=42; set session rpl_semi_sync_master_timeout=99; ERROR HY000: Variable 'rpl_semi_sync_master_timeout' is a GLOBAL variable and should be set with SET GLOBAL select @@global.rpl_semi_sync_master_timeout; @@global.rpl_semi_sync_master_timeout 42 select @@session.rpl_semi_sync_master_timeout; ERROR HY000: Variable 'rpl_semi_sync_master_timeout' is a GLOBAL variable show global variables like 'rpl_semi_sync_master_timeout'; Variable_name Value rpl_semi_sync_master_timeout 42 show session variables like 'rpl_semi_sync_master_timeout'; Variable_name Value rpl_semi_sync_master_timeout 42 select * from information_schema.global_variables where variable_name='rpl_semi_sync_master_timeout'; VARIABLE_NAME VARIABLE_VALUE RPL_SEMI_SYNC_MASTER_TIMEOUT 42 select * from information_schema.session_variables where variable_name='rpl_semi_sync_master_timeout'; VARIABLE_NAME VARIABLE_VALUE RPL_SEMI_SYNC_MASTER_TIMEOUT 42 set global rpl_semi_sync_master_timeout=1.1; ERROR 42000: Incorrect argument type to variable 'rpl_semi_sync_master_timeout' set global rpl_semi_sync_master_timeout=1e1; ERROR 42000: Incorrect argument type to variable 'rpl_semi_sync_master_timeout' set global rpl_semi_sync_master_timeout="some text"; ERROR 42000: Incorrect argument type to variable 'rpl_semi_sync_master_timeout' SET @@global.rpl_semi_sync_master_timeout = @start_global_value; select @@global.rpl_semi_sync_master_timeout; @@global.rpl_semi_sync_master_timeout 10000 UNINSTALL PLUGIN rpl_semi_sync_master;