Version Tokens plugins and loadable functions, see Section 5.6.1, “Installing and Uninstalling Plugins” , and Section 5.7.1, “Installing and Uninstalling Loadable Functions” . To be usable by the server, the plugin library file must be located in the MySQL plugin directory (the directory named by the  plugin_dir  system variable). If necessary, configure the plugin directory location by setting the value of  plugin_dir  at server startup. The plugin library file base name is  version_tokens . The file name suffix differs per platform (for example,  .so  for Unix and Unix-like systems,  .dll  for Windows). To install the Version Tokens plugin and functions, use the  INSTALL PLUGIN  and  CREATE FUNCTION statements, adjusting the  .so  suffix for your platform as necessary: You must install the functions to manage the server’s version token list, but you must also install the plugin because the functions do not work correctly without it. If the plugin and functions are used on a replication source server, install them on all replica servers as well to avoid replication problems. Once installed as just described, the plugin and functions remain installed until uninstalled. To remove them, use the  UNINSTALL PLUGIN  and  DROP FUNCTION  statements: Before using Version Tokens, install it according to the instructions provided at Section 5.6.6.2, “Installing or Uninstalling Version Tokens” . A scenario in which Version Tokens can be useful is a system that accesses a collection of MySQL servers but needs to manage them for load balancing purposes by monitoring them and adjusting server assignments according to load changes. Such a system comprises these elements: INSTALL PLUGIN version_tokens SONAME ’version_token.so’; CREATE FUNCTION version_tokens_set RETURNS STRING SONAME ’version_token.so’; CREATE FUNCTION version_tokens_show RETURNS STRING SONAME ’version_token.so’; CREATE FUNCTION version_tokens_edit RETURNS STRING SONAME ’version_token.so’; CREATE FUNCTION version_tokens_delete RETURNS STRING SONAME ’version_token.so’; CREATE FUNCTION version_tokens_lock_shared RETURNS INT SONAME ’version_token.so’; CREATE FUNCTION version_tokens_lock_exclusive RETURNS INT SONAME ’version_token.so’; CREATE FUNCTION version_tokens_unlock RETURNS INT SONAME ’version_token.so’; UNINSTALL PLUGIN version_tokens; DROP FUNCTION version_tokens_set; DROP FUNCTION version_tokens_show; DROP FUNCTION version_tokens_edit; DROP FUNCTION version_tokens_delete; DROP FUNCTION version_tokens_lock_shared; DROP FUNCTION version_tokens_lock_exclusive; DROP FUNCTION version_tokens_unlock; 5.6.6.3 Using Version Tokens •The collection of MySQL servers to be managed. •An administrative or management application that communicates with the servers and organizes them into high-availability groups. Groups serve different purposes, and servers within each group may have different assignments. Assignment of a server within a certain group can change at any time. 1099