5.4.2.1 Error Logging on Windows

On Windows, mysqld uses the --log-error, --pid-file, and --console options to determine whether mysqld writes the error log to the console or a file, and, if to a file, the file name:

• If --console is given, mysqld writes the error log to the console. (--console takes precedence over --log-error if both are given, and the following items regarding --log-error do not apply. Prior to MySQL 5.7, this is reversed: --log-error takes precedence over --console.)

• If --log-error is not given, or is given without naming a file, mysqld writes the error log to a file named host_name.err in the data directory, unless the --pid-file option is specified. In that case, the file name is the PID file base name with a suffix of .err in the data directory.

• If --log-error is given to name a file, mysqld writes the error log to that file (with an .err suffix added if the name has no suffix). The file location is under the data directory unless an absolute path name is given to specify a different location.

If the server writes the error log to the console, it sets the log_error system variable to stderr. Otherwise, the server writes the error log to a file and sets log_error to the file name.

In addition, the server by default writes events and error messages to the Windows Event Log within the Application log:

• Entries marked as Error, Warning, and Note are written to the Event Log, but not messages such as information statements from individual storage engines.

• Event Log entries have a source of MySQL.

• Information written to the Event Log is controlled using the log_syslog system variable, which on Windows is enabled by default. See Section 5.4.2.3, “Error Logging to the System Log”.