select @@global.performance_schema_max_digest_length; @@global.performance_schema_max_digest_length 123 select @@session.max_digest_length; ERROR HY000: Variable 'max_digest_length' is a GLOBAL variable show global variables like 'performance_schema_max_digest_length'; Variable_name Value performance_schema_max_digest_length 123 show session variables like 'performance_schema_max_digest_length'; Variable_name Value performance_schema_max_digest_length 123 select * from information_schema.global_variables where variable_name='performance_schema_max_digest_length'; VARIABLE_NAME VARIABLE_VALUE PERFORMANCE_SCHEMA_MAX_DIGEST_LENGTH 123 select * from information_schema.session_variables where variable_name='performance_schema_max_digest_length'; VARIABLE_NAME VARIABLE_VALUE PERFORMANCE_SCHEMA_MAX_DIGEST_LENGTH 123 set global performance_schema_max_digest_length=1; ERROR HY000: Variable 'performance_schema_max_digest_length' is a read only variable set session performance_schema_max_digest_length=1; ERROR HY000: Variable 'performance_schema_max_digest_length' is a read only variable