Logging for Aurora MySQL databases

Error – Aurora MySQL writes to the error log only on startup, shutdown, and when it encounters errors. A DB instance can go hours or days without new entries being written to the error log. If you see no recent entries, it's because the server didn't encounter an error that would result in a log entry. Error logging is enabled by default. For more information, see Aurora MySQL error logs.

General – The general log provides detailed information about database activity, including all SQL statements executed by the database engine. For more information on enabling general logging and setting logging parameters, see Aurora MySQL slow query and general logs, and The general query log in the MySQL documentation.

Slow query – The slow query log consists of SQL statements that take more than long_query_time seconds to run and require at least min_examined_row_limit rows to be examined. You can use the slow query log to find queries that take a long time to run and are therefore candidates for optimization.

The default value for long_query_time is 10 seconds. We recommend that you start with a high value to identify the slowest queries, then work your way down for fine tuning.

You can also use related parameters, such as log_slow_admin_statements and log_queries_not_using_indexes. Compare rows_examined with rows_returned. If rows_examined is much greater than rows_returned, then those queries can potentially be blocking.

In Aurora MySQL version 3, you can enable log_slow_extra to obtain more details. For more information, see Slow query log contents in the MySQL documentation. You can also modify long_query_time at the session level for debugging query execution interactively, which is especially useful if log_slow_extra is enabled globally.

For more information on enabling slow query logging and setting logging parameters, see Aurora MySQL slow query and general logs, and The slow query log in the MySQL documentation.

Audit – The audit log monitors and logs database activity. Audit logging for Aurora MySQL is called Advanced Auditing. To enable Advanced Auditing, you set certain DB cluster parameters. For more information, see Using Advanced Auditing with an Amazon Aurora MySQL DB cluster.

Binary – The binary log (binlog) contains events that describe database changes, such as table creation operations and changes to table data. It also contains events for statements that potentially could have made changes (for example, a DELETE that matched no rows), unless row-based logging is used. The binary log also contains information about how long each statement took that updated data.

Running a server with binary logging enabled makes performance slightly slower. However, the benefits of the binary log in enabling you to set up replication and for restore operations generally outweigh this minor performance decrease.

For more information on enabling binary logging and setting the binlog format, see Configuring Aurora MySQL binary logging, and The binary log in the MySQL documentation.