SET @start_global_value = @@global.innodb_old_blocks_time; SELECT @start_global_value; @start_global_value 1000 Valid values are zero or above select @@global.innodb_old_blocks_time >=0; @@global.innodb_old_blocks_time >=0 1 select @@global.innodb_old_blocks_time; @@global.innodb_old_blocks_time 1000 select @@session.innodb_old_blocks_time; ERROR HY000: Variable 'innodb_old_blocks_time' is a GLOBAL variable show global variables like 'innodb_old_blocks_time'; Variable_name Value innodb_old_blocks_time 1000 show session variables like 'innodb_old_blocks_time'; Variable_name Value innodb_old_blocks_time 1000 select * from information_schema.global_variables where variable_name='innodb_old_blocks_time'; VARIABLE_NAME VARIABLE_VALUE INNODB_OLD_BLOCKS_TIME 1000 select * from information_schema.session_variables where variable_name='innodb_old_blocks_time'; VARIABLE_NAME VARIABLE_VALUE INNODB_OLD_BLOCKS_TIME 1000 set global innodb_old_blocks_time=10; select @@global.innodb_old_blocks_time; @@global.innodb_old_blocks_time 10 select * from information_schema.global_variables where variable_name='innodb_old_blocks_time'; VARIABLE_NAME VARIABLE_VALUE INNODB_OLD_BLOCKS_TIME 10 select * from information_schema.session_variables where variable_name='innodb_old_blocks_time'; VARIABLE_NAME VARIABLE_VALUE INNODB_OLD_BLOCKS_TIME 10 set session innodb_old_blocks_time=1; ERROR HY000: Variable 'innodb_old_blocks_time' is a GLOBAL variable and should be set with SET GLOBAL set global innodb_old_blocks_time=1.1; ERROR 42000: Incorrect argument type to variable 'innodb_old_blocks_time' set global innodb_old_blocks_time=1e1; ERROR 42000: Incorrect argument type to variable 'innodb_old_blocks_time' set global innodb_old_blocks_time="foo"; ERROR 42000: Incorrect argument type to variable 'innodb_old_blocks_time' set global innodb_old_blocks_time=-7; Warnings: Warning 1292 Truncated incorrect innodb_old_blocks_time value: '-7' select @@global.innodb_old_blocks_time; @@global.innodb_old_blocks_time 0 select * from information_schema.global_variables where variable_name='innodb_old_blocks_time'; VARIABLE_NAME VARIABLE_VALUE INNODB_OLD_BLOCKS_TIME 0 SET @@global.innodb_old_blocks_time = @start_global_value; SELECT @@global.innodb_old_blocks_time; @@global.innodb_old_blocks_time 1000