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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 cloudsql. logical_decoding is on and wal_sender_timeout is 0. These settings should mostly be pre-configured if you are migrating from another data replication tool.
  1. Click on Edit button on the Overview page.

Edit Button in CloudSQL Postgres

  1. Go to Flags and change cloudsql.logical_decoding to on and wal_sender_timeout to 0. These changes will need restarting your Postgres server.

Change cloudsql.logical_decoding to on

Changed cloudsql.logical_decoding and wal_sender_timeout

Restart Server

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Creating PeerDB User and Granting permissions

Connect to your CloudSQL Postgres through the admin user and run the below commands:
  1. Create a dedicated user for PeerDB: 
    1.      CREATE USER peerdb_user PASSWORD 'some-password';
  2. Grant schema-level, read-only access to the user you created in the previous step. The following example shows permissions for the public schema. Repeat these commands for each schema containing tables you want to replicate: 
    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 privileges to the user: 
    1.      ALTER ROLE peerdb_user REPLICATION;
  4. Create a publication with the tables you want to replicate. We strongly recommend only including the tables you need in the publication to avoid performance overhead.
    Any table included in the publication must either have a primary key defined or have its replica identity configured to FULL.
    1. To create a publication for specific tables:
          CREATE PUBLICATION peerdb_publication FOR TABLE table_to_replicate, table_to_replicate2;
    1. To create a publication for all tables in a specific schema: 
            CREATE PUBLICATION peerdb_publication FOR TABLES IN SCHEMA "public";
    The peerdb_publication publication will contain the set of change events generated from the specified tables, and will later be used to create the MIRROR (replication).
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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Add PeerDB Cloud IPs to Firewall

If you are using PeerDB Cloud, please follow the below steps to add PeerDB IPs to your network.
If your are using SSH Tunnel, then you need to add the PeerDB Cloud IPs to the firewall rules of the Jump Server/Bastion.
  1. Go to Connections section

CloudSQL Connection Connection Section

  1. Go to the Networking subsection

Networking Sub Section in the Conenction Section

  1. Add the public IPs of your PeerDB Cloud instance

Add PeerDB Networks

PeerDB Networks Added

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Create CloudSQL Postgres Peer in PeerDB

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

Choose PostgreSQL Peer

Peer Creation and Validation

Created Peer