System Variables

mysqld maintains many system variables that indicate how it is configured.
- Each system variable has a default value.
- System variables can be set at server startup using options on the command line or in an option file.
- Most of them can be changed dynamically while the server is running by means of the SET statement.
  - Modifies operation of the server without having to stop and restart it.

There are several ways to see the names and values of system variables:
- To see the values that a server will use based on its compiled-in defaults and any option files that it reads, use this command:
- To see the values that a server will use based on its compiled-in defaults, ignoring the settings in any option files, use this command:
- To see the current values used by a running server, use the SHOW VARIABLES statement.

What are the different types of system variables?

© 2007 John Michael Pierobon

Notes