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.