Configuring replication filters with MySQL - Amazon Relational Database Service
Setting replication filtering parameters for RDS for MySQLReplication filtering limitations for RDS for MySQLReplication filtering examples for RDS for MySQLViewing the replication filters for a read replica

Configuring replication filters with MySQL

You can use replication filters to specify which databases and tables are replicated with a read replica. Replication filters can include databases and tables in replication or exclude them from replication.

The following are some use cases for replication filters:

  • To reduce the size of a read replica. With replication filtering, you can exclude the databases and tables that aren't needed on the read replica.

  • To exclude databases and tables from read replicas for security reasons.

  • To replicate different databases and tables for specific use cases at different read replicas. For example, you might use specific read replicas for analytics or sharding.

  • For a DB instance that has read replicas in different AWS Regions, to replicate different databases or tables in different AWS Regions.

Note

You can also use replication filters to specify which databases and tables are replicated with a primary MySQL DB instance that is configured as a replica in an inbound replication topology. For more information about this configuration, see Configuring binary log file position replication with an external source instance.

Setting replication filtering parameters for RDS for MySQL

To configure replication filters, set the following replication filtering parameters on the read replica:

  • replicate-do-db – Replicate changes to the specified databases. When you set this parameter for a read replica, only the databases specified in the parameter are replicated.

  • replicate-ignore-db – Don't replicate changes to the specified databases. When the replicate-do-db parameter is set for a read replica, this parameter isn't evaluated.

  • replicate-do-table – Replicate changes to the specified tables. When you set this parameter for a read replica, only the tables specified in the parameter are replicated. Also, when the replicate-do-db or replicate-ignore-db parameter is set, make sure to include the database that includes the specified tables in replication with the read replica.

  • replicate-ignore-table – Don't replicate changes to the specified tables. When the replicate-do-table parameter is set for a read replica, this parameter isn't evaluated.

  • replicate-wild-do-table – Replicate tables based on the specified database and table name patterns. The % and _ wildcard characters are supported. When the replicate-do-db or replicate-ignore-db parameter is set, make sure to include the database that includes the specified tables in replication with the read replica.

  • replicate-wild-ignore-table – Don't replicate tables based on the specified database and table name patterns. The % and _ wildcard characters are supported. When the replicate-do-table or replicate-wild-do-table parameter is set for a read replica, this parameter isn't evaluated.

The parameters are evaluated in the order that they are listed. For more information about how these parameters work, see the MySQL documentation:

By default, each of these parameters has an empty value. On each read replica, you can use these parameters to set, change, and delete replication filters. When you set one of these parameters, separate each filter from others with a comma.

You can use the % and _ wildcard characters in the replicate-wild-do-table and replicate-wild-ignore-table parameters. The % wildcard matches any number of characters, and the _ wildcard matches only one character.

The binary logging format of the source DB instance is important for replication because it determines the record of data changes. The setting of the binlog_format parameter determines whether the replication is row-based or statement-based. For more information, see Configuring RDS for MySQL binary logging.

Note

All data definition language (DDL) statements are replicated as statements, regardless of the binlog_format setting on the source DB instance.

Replication filtering limitations for RDS for MySQL

The following limitations apply to replication filtering for RDS for MySQL:

  • Each replication filtering parameter has a 2,000-character limit.

  • Commas aren't supported in replication filters for parameter values. In a list of parameters, commas can only be used as value separators. For example, ParameterValue='`a,b`' isn’t supported, but ParameterValue='a,b' is.

  • The MySQL --binlog-do-db and --binlog-ignore-db options for binary log filtering aren't supported.

  • Replication filtering doesn't support XA transactions.

    For more information, see Restrictions on XA Transactions in the MySQL documentation.

Replication filtering examples for RDS for MySQL

To configure replication filtering for a read replica, modify the replication filtering parameters in the parameter group associated with the read replica.

Note

You can't modify a default parameter group. If the read replica is using a default parameter group, create a new parameter group and associate it with the read replica. For more information on DB parameter groups, see Parameter groups for Amazon RDS.

You can set parameters in a parameter group using the AWS Management Console, AWS CLI, or RDS API. For information about setting parameters, see Modifying parameters in a DB parameter group in Amazon RDS. When you set parameters in a parameter group, all of the DB instances associated with the parameter group use the parameter settings. If you set the replication filtering parameters in a parameter group, make sure that the parameter group is associated only with read replicas. Leave the replication filtering parameters empty for source DB instances.

The following examples set the parameters using the AWS CLI. These examples set ApplyMethod to immediate so that the parameter changes occur immediately after the CLI command completes. If you want a pending change to be applied after the read replica is rebooted, set ApplyMethod to pending-reboot.

The following examples set replication filters:

Example Including databases in replication

The following example includes the mydb1 and mydb2 databases in replication.

For Linux, macOS, or Unix:

aws rds modify-db-parameter-group \
  --db-parameter-group-name myparametergroup \
  --parameters "ParameterName=replicate-do-db,ParameterValue='mydb1,mydb2',ApplyMethod=immediate"

For Windows:

aws rds modify-db-parameter-group ^
  --db-parameter-group-name myparametergroup ^
  --parameters "ParameterName=replicate-do-db,ParameterValue='mydb1,mydb2',ApplyMethod=immediate"
Example Including tables in replication

The following example includes the table1 and table2 tables in database mydb1 in replication.

For Linux, macOS, or Unix:

aws rds modify-db-parameter-group \
  --db-parameter-group-name myparametergroup \
  --parameters "ParameterName=replicate-do-table,ParameterValue='mydb1.table1,mydb1.table2',ApplyMethod=immediate"

For Windows:

aws rds modify-db-parameter-group ^
  --db-parameter-group-name myparametergroup ^
  --parameters "ParameterName=replicate-do-table,ParameterValue='mydb1.table1,mydb1.table2',ApplyMethod=immediate"
Example Including tables in replication using wildcard characters

The following example includes tables with names that begin with order and return in database mydb in replication.

For Linux, macOS, or Unix:

aws rds modify-db-parameter-group \
  --db-parameter-group-name myparametergroup \
  --parameters "ParameterName=replicate-wild-do-table,ParameterValue='mydb.order%,mydb.return%',ApplyMethod=immediate"

For Windows:

aws rds modify-db-parameter-group ^
  --db-parameter-group-name myparametergroup ^
  --parameters "ParameterName=replicate-wild-do-table,ParameterValue='mydb.order%,mydb.return%',ApplyMethod=immediate"
Example Excluding databases from replication

The following example excludes the mydb5 and mydb6 databases from replication.

For Linux, macOS, or Unix:

aws rds modify-db-parameter-group \
  --db-parameter-group-name myparametergroup \
  --parameters "ParameterName=replicate-ignore-db,ParameterValue='mydb5,mydb6',ApplyMethod=immediate"

For Windows:

aws rds modify-db-parameter-group ^
  --db-parameter-group-name myparametergroup ^
  --parameters "ParameterName=replicate-ignore-db,ParameterValue='mydb5,mydb6',ApplyMethod=immediate"
Example Excluding tables from replication

The following example excludes tables table1 in database mydb5 and table2 in database mydb6 from replication.

For Linux, macOS, or Unix:

aws rds modify-db-parameter-group \
  --db-parameter-group-name myparametergroup \
  --parameters "ParameterName=replicate-ignore-table,ParameterValue='mydb5.table1,mydb6.table2',ApplyMethod=immediate"

For Windows:

aws rds modify-db-parameter-group ^
  --db-parameter-group-name myparametergroup ^
  --parameters "ParameterName=replicate-ignore-table,ParameterValue='mydb5.table1,mydb6.table2',ApplyMethod=immediate"
Example Excluding tables from replication using wildcard characters

The following example excludes tables with names that begin with order and return in database mydb7 from replication.

For Linux, macOS, or Unix:

aws rds modify-db-parameter-group \
  --db-parameter-group-name myparametergroup \
  --parameters "ParameterName=replicate-wild-ignore-table,ParameterValue='mydb7.order%,mydb7.return%',ApplyMethod=immediate"

For Windows:

aws rds modify-db-parameter-group ^
  --db-parameter-group-name myparametergroup ^
  --parameters "ParameterName=replicate-wild-ignore-table,ParameterValue='mydb7.order%,mydb7.return%',ApplyMethod=immediate"

Viewing the replication filters for a read replica

You can view the replication filters for a read replica in the following ways:

  • Check the settings of the replication filtering parameters in the parameter group associated with the read replica.

    For instructions, see Viewing parameter values for a DB parameter group in Amazon RDS.

  • In a MySQL client, connect to the read replica and run the SHOW REPLICA STATUS statement.

    In the output, the following fields show the replication filters for the read replica:

    • Replicate_Do_DB

    • Replicate_Ignore_DB

    • Replicate_Do_Table

    • Replicate_Ignore_Table

    • Replicate_Wild_Do_Table

    • Replicate_Wild_Ignore_Table

    For more information about these fields, see Checking Replication Status in the MySQL documentation.

    Note

    Previous versions of MySQL used SHOW SLAVE STATUS instead of SHOW REPLICA STATUS. If you are using a MySQL version before 8.0.23, then use SHOW SLAVE STATUS.