MySQL :: MySQL 8.4 Reference Manual :: 7.4.2 The Error Log (original) (raw)

7.4.2 The Error Log

This section discusses how to configure the MySQL server for logging of diagnostic messages to the error log. For information about selecting the error message character set and language, seeSection 12.6, “Error Message Character Set”, andSection 12.12, “Setting the Error Message Language”.

The error log contains a record of mysqld startup and shutdown times. It also contains diagnostic messages such as errors, warnings, and notes that occur during server startup and shutdown, and while the server is running. For example, if mysqld notices that a table needs to be automatically checked or repaired, it writes a message to the error log.

Depending on error log configuration, error messages may also populate the Performance Schemaerror_log table, to provide an SQL interface to the log and enable its contents to be queried. SeeSection 29.12.22.2, “The error_log Table”.

On some operating systems, the error log contains a stack trace ifmysqld exits abnormally. The trace can be used to determine where mysqld exited. SeeSection 7.9, “Debugging MySQL”.

If used to start mysqld,mysqld_safe may write messages to the error log. For example, when mysqld_safe notices abnormal mysqld exits, it restartsmysqld and writes a mysqld restarted message to the error log.

The following sections discuss aspects of configuring error logging.