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Supported Postgres versions

Anything on or after Postgres 12

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Enable Logical Replication

You don’t need to follow the below steps if the settings rds.logical_replication is 1 and wal_sender_timeout is 0. These settings should mostly be pre-configured if you are migrating from another data replication tool.

Checking if the logical replication is already enabled

  1. Create a new parameter group for your Postgres version with rds.logical_replication set to 1; and wal_sender_timeout set to 0.

    Where to find Parameter groups in RDS?

    Changing rds.logical_replication

    Changing wal_sender_timeout

  2. Modify the RDS Postgres database by adding the new parameter group.

    Modifying RDS Postgres with new parameter group

  3. Reboot your RDS Postgres database for the above parameters to kick in.

    Reboot RDS Postgres

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Creating PeerDB User and Granting permissions

Connect to your RDS postgres through the admin user and run the below commands:

  1. Create a Postgres user exclusively for PeerDB.

    1.    CREATE USER peerdb_user PASSWORD 'some-password';

  2. Grant read-only access to the schema from which you are replicating tables to peerdb_user. Below example shows granting permissions for the public schema. If you want to grant access to multiple schemas, you can run these three commands for each schema.

    1.    GRANT USAGE ON SCHEMA "public" TO peerdb_user;
   GRANT SELECT ON ALL TABLES IN SCHEMA "public" TO peerdb_user;
   ALTER DEFAULT PRIVILEGES IN SCHEMA "public" GRANT SELECT ON TABLES TO peerdb_user;

  3. Grant replication access to this user:

    1.    GRANT rds_replication TO peerdb_user ;

  4. Create publication that you’ll be using for creating the MIRROR (replication) in future.

    1.    CREATE PUBLICATION peerdb_publication FOR ALL TABLES;

The PeerDB user must not be restricted by RLS policies, as it can lead to missing data. You can disable RLS policies for the user by running the below command:

ALTER USER peerdb_user BYPASSRLS;

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PeerDB SSH Tunneling Guide (Optional)

Sometimes to connect to your Postgres database you may need PeerDB to use an SSH tunnel.

This is typically used when your database is not publicly accessible and you need to connect to it a jump server in your VPC.

This is done by creating an SSH tunnel to your jump server and then connecting to the database through the tunnel. All of this is handled by PeerDB natively.

1

Generate a key-pair

Generate a key-pair using the following command:

ssh-keygen -t rsa -b 4096 -C "peerdb-ssh-tunnel" -f peerdb_key.pem

This will generate a private key (peerdb_key.pem) and a public key (peerdb_key.pub).

2

Add public key to your jump server

Add the public key to your jump server. This can be done by adding the public key to the ~/.ssh/authorized_keys file on the jump server.

# On the jump server
cat peerdb_key.pub >> ~/.ssh/authorized_keys
3

Add private key to the connection

When creating a Postgres peer you can specify the option to use an SSH tunnel. There you will be able to provide the private key you generated in the first step along with the jump server details.

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Safe list PeerDB Cloud IPs

If you are using PeerDB Cloud safelist public IPs of your PeerDB Cloud instance by editing the Inbound rules of the Security group in which your RDS Postgres (OR the Jump Server/Bastion if you are using SSH tunneling) is located.

Where to find security group in RDS Postgres?

Edit inbound rules for the above security group

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Create RDS Postgres Peer in PeerDB

Through the PeerDB UI, create the RDS Postgres Peer using the peerdb_user that you created in the previous step.

Create peer drop down

Create RDS Postgres Peer