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1.7.1. MySQL Backup Log Control

MySQL Backup provides status and progress logging. This capability can be enabled or disabled. If logging is enabled, tables in the mysql database or log files can be used as the destinations for log output. These features are similar to those provided for the general query log and slow query log (see Selecting General Query and Slow Query Log Output Destinations), although the options and variables are different.

This section describes how to control MySQL Backup logging. For a description of what is logged, see Section 1.7.2, “MySQL Backup Log Contents”.

Log control at server startup. The --log-backup-output option specifies the destination for log output, if logging is enabled, but the option does not in itself enable the logs. The syntax for this option is --log-backup-output[=value,...]:

  • If --log-backup-output is given with a value, the value can be a comma-separated list of one or more of the words TABLE (log to tables), FILE (log to files), or NONE (do not log to tables or files). NONE, if present, takes precedence over any other specifiers.

  • If --log-backup-output is omitted or given without a value, the default logging destination is TABLE.

The --backup_history_log and --backup_progress_log variables control how logging is done to the history and progress logs for the selected log destinations. (By default, both logs are enabled.) These options take an optional argument of 1 or 0 to enable or disable the log. If either log is enabled, the server opens the corresponding log file and writes startup messages to it. However, further logging to the file does not occur unless the FILE log destination is selected.

Examples:

  • With no logging arguments, MySQL Backup logs to the log tables by default.

  • To write log entries to the log tables and log files, use --log-backup-output=TABLE,FILE to select both log destinations.

Log control at runtime. Several system variables are associated with log tables and files and enable runtime control over logging:

  • The log_backup_output system variable indicates the current logging destinations. It can be modified at runtime to change the destinations.

  • The backup_history_log and backup_progress_log variables indicate whether the history and progress logs are enabled (ON) or disabled (OFF). You can set these variables at runtime to control whether the logs are enabled.

  • The backup_history_log_file and backup_progress_log_file variables indicate the names of the history and progress log files. You can set these variables at runtime to change the names of the log files.