MySQL Server has several logs that can help you find out what activity is taking place.

By default, all log files are created in the data directory. You can force the server to close and reopen the log files (or in some cases switch to a new log file) by flushing the logs. Log flushing occurs when you issue a FLUSH LOGS statement or execute a mysqladmin flush-logs, mysqladmin refresh, mysqldump --flush-logs, or mysqldump --master-data command. See Section 12.4.6.2, “FLUSH Syntax”, Section 4.5.2, “mysqladmin — Client for Administering a MySQL Server”, and Section 4.5.4, “mysqldump — A Database Backup Program”. In addition, the binary log is flushed when its size reaches the value of the max_binlog_size system variable.

The relay log is used only on slave replication servers, to hold data changes from the master server that must also be made on the slave. For discussion of relay log contents and configuration, see Section 14.3.2, “The Slave Relay Log”.

For information about log maintenance operations such as expiration of old log files, see Section 5.3.6, “Server Log Maintenance”.

See Section 5.4.2.1, “Administrator Guidelines for Password Security”, for information about keeping logs secure.