Performance Schema System Variable Tables • SERVER • USER • VARIABLE_PATH • MIN_VALUE ,  MAX_VALUE • SET_TIME • SET_USER ,  SET_HOST •Display variables set on the command line: 5034 mysql>  SELECT VARIABLE_NAME FROM performance_schema.variables_info WHERE VARIABLE_SOURCE = ’COMMAND_LINE’ ORDER BY VARIABLE_NAME; +---------------+ The variable was set from a server-specific  $MYSQL_HOME/my.cnf  option file. For details about how MYSQL_HOME  is set, see Section 4.2.2.2, “Using Option Files” . The variable was set from a user-specific  ~/.my.cnf  option file. If the variable was set from an option file,  VARIABLE_PATH  is the path name of that file. Otherwise, the value is the empty string. The minimum and maximum permitted values for the variable. Both are 0 for variables that have no such values (that is, variables that are not numeric). The time at which the variable was most recently set. The default is the time at which the server initialized global system variables during startup. The user name and host name of the client user that most recently set the variable. If a client connects as  user17  from host  host34.example.com  using the account  ’user17’@’%.example.com , SET_USER  and  SET_HOST  are  user17  and  host34.example.com , respectively. For proxy user connections, these values correspond to the external (proxy) user, not the proxied user against which privilege checking is performed. The default for each column is the empty string, indicating that the variable has not been set since server startup. The  variables_info  table has no 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: