资料内容：
7.6.6.1 Version Tokens Elements
Version Tokens is based on a plugin library that implements these elements:
• A server-side plugin named version_tokens holds the list of version tokens associated with the
server and subscribes to notifications for statement execution events. The version_tokens plugin
uses the audit plugin API to monitor incoming statements from clients and matches each client's
session-specific version token list against the server version token list. If there is a match, the plugin
lets the statement through and the server continues to process it. Otherwise, the plugin returns an
error to the client and the statement fails.
• A set of loadable functions provides an SQL-level API for manipulating and inspecting the list of
server version tokens maintained by the plugin. The VERSION_TOKEN_ADMIN privilege (or the
deprecated SUPER privilege) is required to call any of the Version Token functions.
• When the version_tokens plugin loads, it defines the VERSION_TOKEN_ADMIN dynamic
privilege. This privilege can be granted to users of the functions.
• A system variable enables clients to specify the list of version tokens that register the required server
state. If the server has a different state when a client sends a statement, the client receives an error.
