define() is notoriously slow. Since the main benefit of
APC is to increase the performance of scripts/applications, this mechanism
is provided to streamline the process of mass constant definition.
To remove a set of stored constants (without clearing the entire cache), an
empty array may be passed as the constants
parameter, effectively clearing the stored value(s).
The key serves as the name of the constant set
being stored. This key is used to retrieve the
stored constants in apc_load_constants().
An associative array of constant_name => value
pairs. The constant_name must follow the normal
constant naming rules.
value must evaluate to a scalar value.
The default behaviour for constants is to be declared case_sensitive;
i.e. CONSTANT and Constant
represent different values. If this parameter evaluates to FALSE the
constants will be declared as case_insensitive symbols.