Using System Variables Variable Name Variable Type Variable Scope unique_checks Boolean Both updatable_views_with_limit Boolean Both use_secondary_engine Enumeration Session validate_password_check_user_name Boolean Global validate_password_dictionary_file File name Global validate_password_length Integer Global validate_password_mixed_case_count Integer Global validate_password_number_count Integer Global validate_password_policy Enumeration Global validate_password_special_char_count Integer Global validate_password.check_user_name Boolean Global validate_password.dictionary_file File name Global validate_password.length Integer Global validate_password.mixed_case_count Integer Global validate_password.number_count Integer Global validate_password.policy Enumeration Global validate_password.special_char_count Integer Global version_tokens_session String Both wait_timeout Integer Both windowing_use_high_precision Boolean Both 5.1.9.3 Persisted System Variables The MySQL server maintains system variables that configure its operation. A system variable can have a global value that affects server operation as a whole, a session value that affects the current session, or both. Many system variables are dynamic and can be changed at runtime using the  SET  statement to affect operation of the current server instance.  SET  can also be used to persist certain global system variables to the  mysqld-auto.cnf  file in the data directory, to affect server operation for subsequent startups.  RESET PERSIST  removes persisted settings from  mysqld-auto.cnf . The following discussion describes aspects of persisting system variables: The capability of persisting global system variables at runtime enables server configuration that persists across server startups. Although many system variables can be set at startup from a  my.cnf  option file, or at runtime using the  SET  statement, those methods of configuring the server either require login access to the server host, or do not provide the capability of persistently configuring the server at runtime or remotely: Overview of Persisted System Variables •Format and Server Handling of the mysqld-auto.cnf File •Overview of Persisted System Variables •Syntax for Persisting System Variables •Obtaining Information About Persisted System Variables 938