Setting up logical replication for your Aurora PostgreSQL DB cluster

To set up PostgreSQL logical replication for an Aurora PostgreSQL DB cluster

1. Sign in to the Amazon Web Services Management Console and open the Amazon RDS console at https://console.amazonaws.cn/rds/.

2. In the navigation pane, choose your Aurora PostgreSQL DB cluster.

3. Open the Configuration tab. Among the Instance details, find the Parameter group link with DB cluster parameter group for Type.

4. Choose the link to open the custom parameters associated with your Aurora PostgreSQL DB cluster.

5. In the Parameters search field, type rds to find the rds.logical_replication parameter. The default value for this parameter is 0, meaning that it's turned off by default.

6. Choose Edit parameters to access the property values, and then choose 1 from the selector to turn on the feature. Depending on your expected usage, you might also need to change the settings for the following parameters. However, in many cases, the default values are sufficient.

   • max_replication_slots – Set this parameter to a value that's at least equal to your planned total number of logical replication publications and subscriptions. If you are using Amazon DMS, this parameter should equal at least your planned change data capture tasks from the cluster, plus logical replication publications and subscriptions.

   • max_wal_senders and max_logical_replication_workers – Set these parameters to a value that's at least equal to the number of logical replication slots that you intend to be active, or the number of active Amazon DMS tasks for change data capture. Leaving a logical replication slot inactive prevents the vacuum from removing obsolete tuples from tables, so we recommend that you monitor replication slots and remove inactive slots as needed.

   • max_worker_processes – Set this parameter to a value that's at least equal to the total of the max_logical_replication_workers, autovacuum_max_workers, and max_parallel_workers values. On small DB instance classes, background worker processes can affect application workloads, so monitor the performance of your database if you set max_worker_processes higher than the default value. (The default value is the result of GREATEST(${DBInstanceVCPU*2},8}, which means that, by default, this is either 8 or twice the CPU equivalent of the DB instance class, whichever is greater).

   Note

   You can modify parameter values in a customer-created DB parameter group. you can't change the parameter values in a default DB parameter group.

7. Choose Save changes.

8. Reboot the writer instance of your Aurora PostgreSQL DB cluster so that your changes takes effect. In the Amazon RDS console, choose the primary DB instance of the cluster and choose Reboot from the Actions menu.

9. When the instance is available, you can verify that logical replication is turned on, as follows.

   1. Use psql to connect to the writer instance of your Aurora PostgreSQL DB cluster.

      psql --host=your-db-cluster-instance-1.aws-region.rds.amazonaws.com --port=5432 --username=postgres --password --dbname=labdb

   2. Verify that logical replication has been enabled by using the following command.

      labdb=> SHOW rds.logical_replication;
       rds.logical_replication
      -------------------------
       on
      (1 row)

   3. Verify that the wal_level is set to logical.

      labdb=> SHOW wal_level;
        wal_level
      -----------
       logical
      (1 row)