Replicate data from one Neon project to another

Neon's logical replication feature allows you to replicate data from one Neon project to another. This enables different replication scenarios, including:

• Postgres version migration: Moving data from one Postgres version to another; for example, from a Neon project that runs Postgres 15 to one that runs Postgres 16.
• Region migration: Moving data from one region to another; for example, from a Neon project in one region to a Neon project in a different region.
• Neon account migration: Moving data from a Neon project owned by one account to a project owned by a different account; for example, from a personal Neon account to a business-owned Neon account.

These are some common Neon-to-Neon replication scenarios. There may be others. You can follow the steps in this guide for any scenario that requires replicating data between different Neon projects.

Prerequisites

• A Neon project with a database containing the data you want to replicate. If you're just testing this out and need some data to play with, you can use the following statements to create a table with sample data:

  CREATE TABLE IF NOT EXISTS playing_with_neon(id SERIAL PRIMARY KEY, name TEXT NOT NULL, value REAL);
  INSERT INTO playing_with_neon(name, value)
  SELECT LEFT(md5(i::TEXT), 10), random() FROM generate_series(1, 10) s(i);

• A destination Neon project.

• Read the important notices about logical replication in Neon before you begin.

For information about creating a Neon project, see Create a project.

Prepare your source Neon database

This section describes how to prepare your source Neon database (the publisher) for replicating data to your destination Neon database (the subscriber).

Enable logical replication in the source Neon project

In the Neon project containing your source database, enable logical replication. You only need to perform this step on the source Neon project.

To enable logical replication:

1. Select your project in the Neon Console.
2. On the Neon Dashboard, select Settings.
3. Select Logical Replication.
4. Click Enable to enable logical replication.

You can verify that logical replication is enabled by running the following query:

SHOW wal_level;
 wal_level
-----------
 logical

Create a publication on the source database

Publications are a fundamental part of logical replication in Postgres. They define what will be replicated. To create a publication for all tables in your database:

CREATE PUBLICATION my_publication FOR ALL TABLES;

CREATE PUBLICATION playing_with_neon_publication FOR TABLE playing_with_neon;

Prepare your Neon destination database

This section describes how to prepare your destination Neon Postgres database (the subscriber) to receive replicated data.

Prepare your database schema

When configuring logical replication in Postgres, the tables in the source database you are replicating from must also exist in the destination database, and they must have the same table names and columns. You can create the tables manually in your destination database or use utilities like pg_dump and pg_restore to dump the schema from your source database and load it to your destination database. See Import a database schema for instructions.

If you're using the sample playing_with_neon table, you can create the same table on the destination database with the following statement:

CREATE TABLE IF NOT EXISTS playing_with_neon(id SERIAL PRIMARY KEY, name TEXT NOT NULL, value REAL);

Create a subscription

After creating a publication on the source database, you need to create a subscription on the destination database.

1. Use the Neon SQL Editor, psql, or another SQL client to connect to your destination database.

2. Create the subscription using the using a CREATE SUBSCRIPTION statement.

   CREATE SUBSCRIPTION my_subscription
   CONNECTION 'postgresql://neondb_owner:<password>@ep-cool-darkness-123456.us-east-2.aws.neon.tech/neondb'
   PUBLICATION my_publication;

   • subscription_name: A name you chose for the subscription.
   • connection_string: The connection string for the source Neon database where you defined the publication.
   • publication_name: The name of the publication you created on the source Neon database.

3. Verify the subscription was created by running the following command:

   SELECT * FROM pg_stat_subscription;

   The subscription (my_subscription) should be listed, confirming that your subscription has been created successfully.

Test the replication

Testing your logical replication setup ensures that data is being replicated correctly from the publisher to the subscriber database.

1. Run some data modifying queries on the source database (inserts, updates, or deletes). If you're using the playing_with_neon database, you can use this statement to insert some rows:

   INSERT INTO playing_with_neon(name, value)
   SELECT LEFT(md5(i::TEXT), 10), random() FROM generate_series(1, 10) s(i);

2. Perform a row count on the source and destination databases to make sure the result matches.

   SELECT COUNT(*) FROM playing_with_neon;
   
   count
   -------
   30
   (1 row)

Alternatively, you can run the following query on the subscriber to make sure the last_msg_receipt_time is as expected. For example, if you just ran an insert option on the publisher, the last_msg_receipt_time should reflect the time of that operation.

SELECT subname, received_lsn, latest_end_lsn, last_msg_receipt_time FROM pg_catalog.pg_stat_subscription;

Switch over your application

After the replication operation is complete, you can switch your application over to the destination database by swapping out your source database connection details for your destination database connection details.

You can find the connection details for a Neon database on the Connection Details widget in the Neon Console. For details, see Connect from any application.