SET @start_global_value = @@global.flush_time;

#
# exists as global only
#
select @@global.flush_time;
--error ER_INCORRECT_GLOBAL_LOCAL_VAR
select @@session.flush_time;
show global variables like 'flush_time';
show session variables like 'flush_time';
select * from information_schema.global_variables where variable_name='flush_time';
select * from information_schema.session_variables where variable_name='flush_time';

#
# show that it's writable
#
set global flush_time=1;
select @@global.flush_time;
--error ER_GLOBAL_VARIABLE
set session flush_time=1;

#
# incorrect types
#
--error ER_WRONG_TYPE_FOR_VAR
set global flush_time=1.1;
--error ER_WRONG_TYPE_FOR_VAR
set global flush_time=1e1;
--error ER_WRONG_TYPE_FOR_VAR
set global flush_time="foo";

#
# min/max values
#
set global flush_time=0;
select @@global.flush_time;
set global flush_time=cast(-1 as unsigned int);
select @@global.flush_time;

SET @@global.flush_time = @start_global_value;