content_image/704953.jpg
<img src='content_image/704953.jpg'>

## 5.1.9.3 Persisted System Variables 

The MySQL server maintains system variables that configure its operation. A system variable can have a global value that affects server operation as a whole, a session value that affects the current session, or both. Many system variables are dynamic and can be changed at runtime using the SET  statement to affect operation of the current server instance. SET  can also be used to persist certain global system variables to the mysqld-auto.cnf  file in the data directory, to affect server operation for subsequent startups. RESET PERSIST  removes persisted settings from mysqld-auto.cnf . 

## Overview of Persisted System Variables 

The following discussion describes aspects of persisting system variables: 

•Overview of Persisted System Variables 

•Syntax for Persisting System Variables 

•Obtaining Information About Persisted System Variables 

•Format and Server Handling of the mysqld-auto.cnf File 

The capability of persisting global system variables at runtime enables server configuration that persists across server startups. Although many system variables can be set at startup from a my.cnf  option file, or at runtime using the SET  statement, those methods of configuring the server either require login access to the server host, or do not provide the capability of persistently configuring the server at runtime or remotely: 

