Preparing Your Migration to Heroku Postgres

Last updated March 28, 2025

Migrating to Heroku Postgres from a different managed-PostgreSQL provider is a simple process. With Heroku Postgres, you get low cost, high performance, and easy resource management. In this article, we walk through the prerequisite steps to complete before the migration process. After completing these steps, see our guides on migrating to Heroku Postgres from the following cloud providers:

Our guides use the “dump and restore” migration strategy for your database. If your database is under 100 GB and you can tolerate a few hours of downtime, this strategy fits most use cases.

Our guides only cover the migration process for the listed databases, but you can use the dump and restore strategy with other databases as well, such as on-premise databases.

To learn more about the high-level considerations for migrating Postgres from one cloud provider to another, see Planning Your PostgreSQL Migration.

Downtime Tolerance

The dump and restore approach assumes you can tolerate some downtime in your environment as you migrate. The migration process begins with dumping the entire database schema and data to a file. This step can take minutes or hours, depending on the size of your database. Next, you upload the file to an S3-compatible storage bucket. Finally, using Heroku Postgres, you restore the database from the file.

During the period between dumping the database in storage and restoring it from a file at Heroku, any subsequent updates to the originating database aren’t captured and applied to your Heroku database. It’s important to set your system to read-only mode so you don’t write to the database, or take your systems offline during the migration period.

To be conservative, plan for several hours of downtime.

If your database is attached to a Heroku app, put your app in maintenance mode.

Prerequisites

To start, we assume that you have:

  • A managed instance of Postgres from one of the listed cloud providers
  • Credentials to connect to that database from the command line
  • Access to write to the S3-compatible storage bucket as outlined in each guide
  • A database under 100 GB
  • A Heroku account

Gather Information and Configurations

You need several pieces of information about your Postgres setup at your cloud provider.

1. PostgreSQL version

Use the psql command line utility to connect to your PostgreSQL instance. To see the Postgres version, run the command:

$ psql=> SELECT version();
                                version
--------------------------------------------------------------------------
PostgreSQL 15.8 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 7.3.1 20180712 (Red Hat 7.3.1-12), 64-bit


(1 row)

In our example, we’re using major version 15.

If your PostgreSQL instance runs an older version of Postgres than what Heroku Postgres supports, you must upgrade to a supported version on your cloud provider’s instance first. It’s easier to troubleshoot if you separate the version upgrade process from the migration process.

2. Extensions

You must install the same extensions in your current database in Heroku Postgres later. To list the extensions you installed on your instance, run the command:

$ psql=> \dx
                    List of installed extensions
  Name   | Version |   Schema   |            Description
---------+---------+------------+------------------------------------
 plpgsql | 1.0     | pg_catalog | PL/pgSQL procedural language
 sslinfo | 1.2     | public     | information about SSL certificates

(2 rows)

Azure database instances include the azure and pgaadauth extensions. You don’t need to install these extensions after migrating to Heroku Postgres.

3. Other Configurations

To capture the configurations for your Postgres database at your cloud provider, you can run psql with a Postgres command to dump your settings to a file:

$ psql postgres://DB_USERNAME:DB_PASSWORD@DB_HOST:DB_PORT/DB_NAME \
    -c "\copy (select * from pg_settings) to '/tmp/settings_postgres.csv' with (format csv, header true);"

The command outputs all settings for your database to /tmp/settings_postgres.csv. Make sure to insert your Postgres credentials and connection information in the Postgres URI.

4. Applications and Services Your Database Uses

Next, gather a list of applications, services, APIs, or other systems that connect to your database. When the time comes to cut over from your cloud provider’s PostgreSQL to Heroku Postgres, you must modify the connection information for each system.

Next Steps

Now that you know your current Postgres version and configuration details, you can start the migration process by following one of our guides for your cloud provider’s PostgreSQL instance.

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