Configuring MySQL binary logging

The binary log is a set of log files that contain information about data modifications made to an MySQL server instance. The binary log contains information such as the following:

• Events that describe database changes such as table creation or row modifications

• Information about the duration of each statement that updated data

• Events for statements that could have updated data but didn't

The binary log records statements that are sent during replication. It is also required for some recovery operations. For more information, see The Binary Log and Binary Log Overview in the MySQL documentation.

The automated backups feature determines whether binary logging is turned on or off for MySQL. You have the following options:

Turn binary logging on

Set the backup retention period to a positive nonzero value.

Turn binary logging off

Set the backup retention period to zero.

For more information, see Enabling automated backups.

MySQL on Amazon RDS supports the row-based, statement-based, and mixed binary logging formats. We recommend mixed unless you need a specific binlog format. For details on the different MySQL binary log formats, see Binary logging formats in the MySQL documentation.

If you plan to use replication, the binary logging format is important because it determines the record of data changes that is recorded in the source and sent to the replication targets. For information about the advantages and disadvantages of different binary logging formats for replication, see Advantages and disadvantages of statement-based and row-based replication in the MySQL documentation.

Important

Setting the binary logging format to row-based can result in very large binary log files. Large binary log files reduce the amount of storage available for a DB instance and can increase the amount of time to perform a restore operation of a DB instance.

Statement-based replication can cause inconsistencies between the source DB instance and a read replica. For more information, see Determination of safe and unsafe statements in binary logging in the MySQL documentation.

Enabling binary logging increases the number of write disk I/O operations to the DB instance. You can monitor IOPS usage with the WriteIOPS CloudWatch metric.

To set the MySQL binary logging format

1. Open the Amazon RDS console at https://console.aws.amazon.com/rds/.

2. In the navigation pane, choose Parameter groups.

3. Choose the DB parameter group, associated with the DB instance, that you want to modify.

   You can't modify a default parameter group. If the DB instance is using a default parameter group, create a new parameter group and associate it with the DB instance.

   For more information on parameter groups, see Working with parameter groups.

4. From Actions, choose Edit.

5. Set the binlog_format parameter to the binary logging format of your choice (ROW, STATEMENT, or MIXED).

   You can turn off binary logging by setting the backup retention period of a DB instance to zero, but this disables daily automated backups. Disabling automated backups turns off or disables the log_bin session variable. This disables binary logging on the RDS for MySQL DB instance, which in turn resets the binlog_format session variable to the default value of ROW in the database. We recommend that you don't disable backups. For more information about the Backup retention period setting, see Settings for DB instances.

6. Choose Save changes to save the updates to the DB parameter group.

Because the binlog_format parameter is dynamic, you don't need to reboot the DB instance for the changes to apply.

Important

Changing a DB parameter group affects all DB instances that use that parameter group. If you want to specify different binary logging formats for different MySQL DB instances in an AWS Region, the DB instances must use different DB parameter groups. These parameter groups identify different logging formats. Assign the appropriate DB parameter group to the each DB instance.