SELECT COUNT(@@GLOBAL.mysqlx_ssl_key); COUNT(@@GLOBAL.mysqlx_ssl_key) 1 SET @@GLOBAL.mysqlx_ssl_key=1; ERROR HY000: Variable 'mysqlx_ssl_key' is a read only variable Expected error 'Read only variable' SELECT COUNT(@@GLOBAL.mysqlx_ssl_key); COUNT(@@GLOBAL.mysqlx_ssl_key) 1 SELECT @@GLOBAL.mysqlx_ssl_key = VARIABLE_VALUE FROM performance_schema.global_variables WHERE VARIABLE_NAME='mysqlx_ssl_key'; @@GLOBAL.mysqlx_ssl_key = VARIABLE_VALUE 1 SELECT COUNT(VARIABLE_VALUE) FROM performance_schema.global_variables WHERE VARIABLE_NAME='mysqlx_ssl_key'; COUNT(VARIABLE_VALUE) 1 SELECT @@mysqlx_ssl_key = @@GLOBAL.mysqlx_ssl_key; @@mysqlx_ssl_key = @@GLOBAL.mysqlx_ssl_key 1 SELECT COUNT(@@mysqlx_ssl_key); COUNT(@@mysqlx_ssl_key) 1 SELECT COUNT(@@local.mysqlx_ssl_key); ERROR HY000: Variable 'mysqlx_ssl_key' is a GLOBAL variable Expected error 'Variable is a GLOBAL variable' SELECT COUNT(@@SESSION.mysqlx_ssl_key); ERROR HY000: Variable 'mysqlx_ssl_key' is a GLOBAL variable Expected error 'Variable is a GLOBAL variable' SELECT COUNT(@@GLOBAL.mysqlx_ssl_key); COUNT(@@GLOBAL.mysqlx_ssl_key) 1 SELECT mysqlx_ssl_key = @@SESSION.mysqlx_ssl_key; ERROR 42S22: Unknown column 'mysqlx_ssl_key' in 'field list' Expected error 'Readonly variable'