Using System Variables GRANT SESSION_VARIABLES_ADMIN ON *.* TO set_session_sysvars; REVOKE SYSTEM_VARIABLES_ADMIN ON *.* FROM set_session_sysvars; 921 Variable Name Variable Type Variable Scope activate_all_roles_on_login Boolean Global admin_ssl_ca File name Global admin_ssl_capath Directory name Global admin_ssl_cert File name Global admin_ssl_cipher String Global admin_ssl_crl File name Global admin_ssl_crlpath Directory name Global admin_ssl_key File name Global admin_tls_ciphersuites String Global admin_tls_version String Global audit_log_connection_policy Enumeration Global audit_log_exclude_accounts String Global audit_log_flush Boolean Global audit_log_include_accounts String Global audit_log_max_size Integer Global audit_log_password_history_keep_days Integer Global audit_log_prune_seconds Integer Global audit_log_read_buffer_size Integer Varies audit_log_rotate_on_size Integer Global Table 5.4 Dynamic System Variable Summary Variables that have a type of “string”  take a string value. Variables that have a type of “numeric”  take a numeric value. Variables that have a type of “boolean”  can be set to 0, 1,  ON  or  OFF . Variables that are marked as “enumeration”  normally should be set to one of the available values for the variable, but can also be set to the number that corresponds to the desired enumeration value. For enumerated system variables, the first enumeration value corresponds to 0. This differs from the  ENUM  data type used for table columns, for which the first enumeration value corresponds to 1. The table lists each variable’s data type and scope. The last column indicates whether the scope for each variable is Global, Session, or both. Please see the corresponding item descriptions for details on setting and using the variables. Where appropriate, direct links to further information about the items are provided. Many server system variables are dynamic and can be set at runtime. See Section 13.7.6.1, “SET Syntax for Variable Assignment” . For a description of the privilege requirements for setting system variables, see Section 5.1.9.1, “System Variable Privileges” The following table lists all dynamic system variables applicable within  mysqld . Modifying the role has an immediate effect: Any account granted the  set_session_sysvars  role no longer has  SYSTEM_VARIABLES_ADMIN  and is not able to set global system variables without being granted that ability explicitly. A similar  GRANT / REVOKE  sequence can be applied to any account that was granted  SYSTEM_VARIABLES_ADMIN  directly rather than by means of a role. 5.1.9.2 Dynamic System Variables