The Error Log •Enable the component by listing it in the  log_error_services  value. •For a component to be permitted in the  log_error_services  value, it must be known. A component is known if it is built in, or if it is loadable and has been loaded using  INSTALL COMPONENT . Attempts to name an unknown component at server startup cause  log_error_services  to be set to its default value. Attempts to name an unknown component at runtime produce an error and the log_error_services  value remains unchanged. •To disable a log component, remove it from the  log_error_services  value. Then, if the component is loadable and you also want to unload it, use  UNINSTALL COMPONENT . 1. If the component is loadable, load it at runtime using  INSTALL COMPONENT . Loading the component registers it in the  mysql.component  system table so that the server loads it automatically for subsequent startups. 2. Set the  log_error_services  value at startup to include the component name. Set the value either in the server  my.cnf  file, or use  SET PERSIST , which sets the value for the running MySQL instance and also saves the value to be used for subsequent server restarts; see Section 13.7.6.1, “SET Syntax for Variable Assignment” . A value set in  my.cnf  takes effect at the next restart. A value set using  SET PERSIST  takes effect immediately, and for subsequent restarts. Attempts to use  UNINSTALL COMPONENT  to unload a loadable component that is still named in the log_error_services  value produce an error. For example, to use the system log sink ( log_sink_syseventlog ) instead of the default sink ( log_sink_internal ), first load the sink component, then modify the  log_error_services  value: The URN to use for loading a log component with  INSTALL COMPONENT  is the component name prefixed with  file://component_ . For example, for the log_sink_syseventlog  component, the corresponding URN is  file:// component_log_sink_syseventlog . It is possible to configure multiple log sinks, which enables sending output to multiple destinations. To enable the system log sink in addition to (rather than instead of) the default sink, set the log_error_services  value like this: To revert to using only the default sink and unload the system log sink, execute these statements: To configure a log component to be enabled at each server startup, use this procedure: Suppose that you want to configure, for every server startup, use of the JSON log sink ( log_sink_json ) in addition to the built-in log filter and sink ( log_filter_internal ,  log_sink_internal ). First load the JSON sink if it is not loaded: Then set  log_error_services  to take effect at server startup. You can set it in  my.cnf : 1027 [mysqld] INSTALL COMPONENT ’file://component_log_sink_json’; SET GLOBAL log_error_services = ’log_filter_internal; log_sink_internal; UNINSTALL COMPONENT ’file://component_log_sink_syseventlog’; SET GLOBAL log_error_services = ’log_filter_internal; log_sink_internal; log_sink_syseventlog’; INSTALL COMPONENT ’file://component_log_sink_syseventlog’; SET GLOBAL log_error_services = ’log_filter_internal; log_sink_syseventlog’; Note