MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0

26.12.13.2 Performance Schema variables_info Table

The variables_info table shows, for each system variable, the source from which it was most recently set, and its range of values.

variables_info has these columns:

The variables_info table has these indexes:

TRUNCATE TABLE is not permitted for the variables_info table.

If a variable with a VARIABLE_SOURCE value other than DYNAMIC is set at runtime, VARIABLE_SOURCE becomes DYNAMIC and VARIABLE_PATH becomes the empty string.

A system variable that has only a session value (such as debug_sync) cannot be set at startup or persisted. For session-only system variables, VARIABLE_SOURCE can be only COMPILED or DYNAMIC.

If a system variable has an unexpected VARIABLE_SOURCE value, consider your server startup method. For example, mysqld_safe reads option files and passes certain options it finds there as part of the command line that it uses to start mysqld. Consequently, some system variables that you set in option files might display in variables_info as COMMAND_LINE, rather than as GLOBAL or SERVER as you might otherwise expect.

Some sample queries that use the variables_info table, with representive output: