select @@global.relay_log_info_file;
@@global.relay_log_info_file
relay-log.info
select @@session.relay_log_info_file;
ERROR HY000: Variable 'relay_log_info_file' is a GLOBAL variable
show global variables like 'relay_log_info_file';
Variable_name	Value
relay_log_info_file	relay-log.info
show session variables like 'relay_log_info_file';
Variable_name	Value
relay_log_info_file	relay-log.info
select * from information_schema.global_variables where variable_name='relay_log_info_file';
VARIABLE_NAME	VARIABLE_VALUE
RELAY_LOG_INFO_FILE	relay-log.info
select * from information_schema.session_variables where variable_name='relay_log_info_file';
VARIABLE_NAME	VARIABLE_VALUE
RELAY_LOG_INFO_FILE	relay-log.info
set global relay_log_info_file=1;
ERROR HY000: Variable 'relay_log_info_file' is a read only variable
set session relay_log_info_file=1;
ERROR HY000: Variable 'relay_log_info_file' is a read only variable