The Error Log The operating system error message. The label corresponding to the  prio  value, as a string. The client user. The client host. The ID of the thread within  mysqld  responsible for producing the error event. This ID indicates which part of the server produced the event, and is consistent with general query log and slow query log messages, which include the connection thread ID. The query ID. The source file in which the event occurred, without any leading path. The line within the source file at which the event occurred. The function in which the event occurred. The component or plugin in which the event occurred. Error log configuration normally includes one log filter component and one or more log sink components. For error log filtering, MySQL offers a choice of components: • log_filter_internal : This filter component provides error log filtering based on log event priority and error code, in combination with the  log_error_verbosity  and log_error_suppression_list  system variables.  log_filter_internal  is built in and enabled by default. See Section 5.4.2.5, “Priority-Based Error Log Filtering (log_filter_internal)” . • log_filter_dragnet : This filter component provides error log filtering based on user-supplied rules, in combination with the  dragnet.log_error_filter_rules  system variable. See Section 5.4.2.6, “Rule-Based Error Log Filtering (log_filter_dragnet)” . • label •Identification of the client for which the event occurred: • user • host • thread • query_id •Debugging information: • source_file • source_line • function • component 5.4.2.4 Types of Error Log Filtering 1032