SET @start_global_value = @@global.innodb_background_scrub_data_check_interval;
#
# default value
#
select @@global.innodb_background_scrub_data_check_interval;
@@global.innodb_background_scrub_data_check_interval
3600
set global innodb_background_scrub_data_check_interval=10;
select @@global.innodb_background_scrub_data_check_interval;
@@global.innodb_background_scrub_data_check_interval
10
set global innodb_background_scrub_data_check_interval=DEFAULT;
select @@global.innodb_background_scrub_data_check_interval;
@@global.innodb_background_scrub_data_check_interval
3600
set global innodb_background_scrub_data_check_interval=20;
select @@global.innodb_background_scrub_data_check_interval;
@@global.innodb_background_scrub_data_check_interval
20
set global innodb_background_scrub_data_check_interval=DEFAULT;
select @@global.innodb_background_scrub_data_check_interval;
@@global.innodb_background_scrub_data_check_interval
3600
#
# exists as global only
#
select @@global.innodb_background_scrub_data_check_interval;
@@global.innodb_background_scrub_data_check_interval
3600
select @@session.innodb_background_scrub_data_check_interval;
ERROR HY000: Variable 'innodb_background_scrub_data_check_interval' is a GLOBAL variable
show global variables like 'innodb_background_scrub_data_check_interval';
Variable_name	Value
innodb_background_scrub_data_check_interval	3600
show session variables like 'innodb_background_scrub_data_check_interval';
Variable_name	Value
innodb_background_scrub_data_check_interval	3600
select * from information_schema.global_variables
where variable_name='innodb_background_scrub_data_check_interval';
VARIABLE_NAME	VARIABLE_VALUE
INNODB_BACKGROUND_SCRUB_DATA_CHECK_INTERVAL	3600
select * from information_schema.session_variables
where variable_name='innodb_background_scrub_data_check_interval';
VARIABLE_NAME	VARIABLE_VALUE
INNODB_BACKGROUND_SCRUB_DATA_CHECK_INTERVAL	3600
#
# show that it's writable
#
set global innodb_background_scrub_data_check_interval=10;
select @@global.innodb_background_scrub_data_check_interval;
@@global.innodb_background_scrub_data_check_interval
10
set global innodb_background_scrub_data_check_interval=20;
select @@global.innodb_background_scrub_data_check_interval;
@@global.innodb_background_scrub_data_check_interval
20
set global innodb_background_scrub_data_check_interval=1;
select @@global.innodb_background_scrub_data_check_interval;
@@global.innodb_background_scrub_data_check_interval
1
set session innodb_background_scrub_data_check_interval=1;
ERROR HY000: Variable 'innodb_background_scrub_data_check_interval' is a GLOBAL variable and should be set with SET GLOBAL
#
# incorrect types
#
set global innodb_background_scrub_data_check_interval=1.1;
ERROR 42000: Incorrect argument type to variable 'innodb_background_scrub_data_check_interval'
set global innodb_background_scrub_data_check_interval=1e1;
ERROR 42000: Incorrect argument type to variable 'innodb_background_scrub_data_check_interval'
set global innodb_background_scrub_data_check_interval="foo";
ERROR 42000: Incorrect argument type to variable 'innodb_background_scrub_data_check_interval'
SET @@global.innodb_background_scrub_data_check_interval = @start_global_value;