CREATE ACCESS METHOD creates a new access method.
The access method name must be unique within the database.
Only superusers can define new access methods.
The name of the access method to be created.
This clause specifies type of access method to define. Only INDEX is supported at present.
handler_function is the name of a previously registered function that will be called to retrieve the struct which contains required parameters and functions of access method to the core. The handler function must take single argument of type internal, and its return type depends on the type of access method; for INDEX access methods, it must be index_am_handler.
See Section 58.1 for index access methods API.