set @mroonga_log_level_backup=@@mroonga_log_level;
show global variables like 'mroonga_log_level';
Variable_name	Value
mroonga_log_level	NOTICE
set global mroonga_log_level=NONE;
show global variables like 'mroonga_log_level';
Variable_name	Value
mroonga_log_level	NONE
set global mroonga_log_level=EMERG;
show global variables like 'mroonga_log_level';
Variable_name	Value
mroonga_log_level	EMERG
set global mroonga_log_level=ALERT;
show global variables like 'mroonga_log_level';
Variable_name	Value
mroonga_log_level	ALERT
set global mroonga_log_level=CRIT;
show global variables like 'mroonga_log_level';
Variable_name	Value
mroonga_log_level	CRIT
set global mroonga_log_level=ERROR;
show global variables like 'mroonga_log_level';
Variable_name	Value
mroonga_log_level	ERROR
set global mroonga_log_level=WARNING;
show global variables like 'mroonga_log_level';
Variable_name	Value
mroonga_log_level	WARNING
set global mroonga_log_level=NOTICE;
show global variables like 'mroonga_log_level';
Variable_name	Value
mroonga_log_level	NOTICE
set global mroonga_log_level=INFO;
show global variables like 'mroonga_log_level';
Variable_name	Value
mroonga_log_level	INFO
set global mroonga_log_level=DEBUG;
show global variables like 'mroonga_log_level';
Variable_name	Value
mroonga_log_level	DEBUG
set global mroonga_log_level=DUMP;
show global variables like 'mroonga_log_level';
Variable_name	Value
mroonga_log_level	DUMP
set global mroonga_log_level=dummy;
ERROR 42000: Variable 'mroonga_log_level' can't be set to the value of 'dummy'
set session mroonga_log_level=NOTICE;
ERROR HY000: Variable 'mroonga_log_level' is a GLOBAL variable and should be set with SET GLOBAL
set global mroonga_log_level=@mroonga_log_level_backup;
