MySQL 5.6 Reference Manual Including MySQL NDB Cluster 7.3-7.4 Reference Guide
Many server system variables are dynamic and can be set at runtime. See Section 13.7.4.1, “SET Syntax for Variable Assignment”. For a description of the privilege requirements for setting system variables, see Section 5.1.8.1, “System Variable Privileges”
The following table lists all dynamic system variables
applicable within mysqld.
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.
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.
Table 5.5 Dynamic System Variable Summary