# bool readonly

#
# show the global and session values;
#
select @@global.mutex_deadlock_detector;
--error ER_INCORRECT_GLOBAL_LOCAL_VAR
select @@session.mutex_deadlock_detector;
show global variables like 'mutex_deadlock_detector';
show session variables like 'mutex_deadlock_detector';
select * from information_schema.global_variables where variable_name='mutex_deadlock_detector';
select * from information_schema.session_variables where variable_name='mutex_deadlock_detector';

#
# show that it's read-only
#
--error ER_INCORRECT_GLOBAL_LOCAL_VAR
set global mutex_deadlock_detector=1;
--error ER_INCORRECT_GLOBAL_LOCAL_VAR
set session mutex_deadlock_detector=1;