Last updated June 18, 2026

In this guide, we walk you through the process of migrating your Postgres database from Aiven for PostgreSQL to Heroku Postgres with a dump and restore strategy. This guide uses AWS S3 to store the database dump file. Before starting the migration, make sure you completed the steps from Preparing Your Migration to Heroku Postgres.

Check Your Database Size

With a managed database from Aiven, you can estimate your database size either through the web UI or through querying the database with the psql client. From your database in AIven, click Metrics in the left-hand navigation pane and find the chart for Disk space usage.

The chart shows the database is using 15.413% of our total storage allocated for this instance. Next, navigate to the Overview page to find Service plan usage.

This page shows us the storage usage percentage at 15.4% out of the total allocation of 5 GB, or approximately 770 MB. However, this number includes all storage for the system running on your managed instance, including system files, installations, and more. So, the actual database size is only a fraction of this number.

Usually, the dump and restore strategy for migration is suitable if your database size is less than 100 GB.

For a more accurate size reading, connect to your database instance and use the list databases \l+ command. You can find the Postgres credentials for your database on the Overview page for your database in the Connection information section. Copy the Service URI, which is the connection string you’ll use to connect via a psql client.

The connection string for using the psql client uses the format:

postgres://DB_USERNAME:DB_PASSWORD@DB_HOST:DB_PORT/DB_NAME

Our example database is called employees, so we connect our database to the psql client with:

$ psql postgres://avnadmin:thisismypassword@pg-25eae734-ds-hero-migration.i.aivencloud.com:11893/employees

After connecting, you can show the database size with the list databases \l+ command:

$ psql=> \l+

                        List of databases
    Name        | Owner     | Encoding |   Collate   | Size   |
----------------+-----------+----------+-------------+--------+
 employees      | avnadmin  | UTF8     | en_US.UTF-8 | 335 MB |

The Size column shows our database size is 335 MB.

See Choosing the Right Heroku Postgres Plan for which Heroku Postgres plan fits your database size.

Create and Upload the Database Dump

Before starting, either set your system to read-only mode, or bring all your dependent services offline and notify end users of the current maintenance status.

Back Up Your Database

Before performing the migration, make sure you have a recent backup of your database on Aiven. Aiven backs up your databases automatically every day. Navigate to the Backups page for your database to check the recency of your latest backup.

Dump the Database to a Local File

Using pg_dump, create a logical backup of your Aiven database to a local file:

$ pg_dump postgres://DB_USERNAME:DB_PASSWORD@DB_HOST:DB_PORT/DB_NAME \
    -Fc -b -v \
    -f /tmp/data-for-migration.sql

The time it takes to run this command varies depending on the size of your database.

Upload the File to AWS S3

Heroku can restore Postgres logical backups that are accessible via a URL. Aiven doesn’t offer an object storage service, so for this migration, we upload our data backup file to AWS S3.

First, create an S3 bucket. In our example, we named our bucket postgres-for-migration.

For security, make sure to block public access to this bucket. When you restore the database from this file, you’ll use a short-lived, signed URL to access the file.

In addition, make sure the S3 bucket uses proper encryption for storage.

After creating your S3 bucket, upload the /tmp/data-for-migration.sql backup file that you created in the Dump the Database to a Local File step.

Restore to Heroku Postgres

Create a Heroku App

Use the Heroku CLI to log into your Heroku account.

$ heroku login

Next, create a Heroku app and provide a name for it, such as postgres-migration-from-aiven.

$ heroku apps:create psql-migration-from-aiven
Creating ⬢ psql-migration-from-aiven... done

Provision a Heroku Postgres Add-on

After creating your Heroku app, add the Heroku Postgres add-on with an appropriate plan.

Based on the database information from Check Your Database Size, we use the essential-1 Heroku Postgres plan.

$ heroku addons:create \
    --app psql-migration-from-aiven \
    heroku-postgresql:essential-1
Creating heroku-postgresql:essential-1 on ⬢ psql-migration-from-aiven... ~$0.013/hour (max $9/month)
Database should be available soon
postgresql-silhouetted-05205 is being created in the background. The app will restart when complete...
Use heroku addons:info postgresql-silhouetted-05205 to check creation progress
Use heroku addons:docs heroku-postgresql to view documentation

Heroku begins provisioning a Postgres database for your Heroku app, providing a unique add-on name. Within a few minutes, you can run the following command with the database name to see the created database.

$ heroku addons:info postgresql-silhouetted-05205
=== postgresql-silhouetted-05205

Plan:         heroku-postgresql:essential-1
Price:        ~$0.013/hour
Max Price:    $9/month
Attachments:  ⬢ psql-migration-from-aiven::DATABASE
Owning app:   ⬢ psql-migration-from-aiven
Installed at: Tue May 19 2026 15:29:01 GMT+0000 (Coordinated Universal Time)
State:        created

Get the Presigned URL for the Backup File in S3

Next, restore your pg_dump backup to your new Heroku Postgres database. To restore, you need a URL that points to your backup file. The S3 bucket you created isn’t public, but you can generate a temporary, presigned URL that points to your uploaded file.

In AWS S3, navigate to the appropriate bucket and file. Under Object actions, select Share with a presigned URL.

Configure the presigned URL with a reasonable expiration time, such as 5-15 minutes, depending on your backup size.

After creating your presigned URL, it’s copied to your clipboard. The URL contains a token and signature as query parameters. It looks similar to this example:

https://postgres-for-migration.s3.us-west-2.amazonaws.com/aiven-data-for-migration.sql?response-content-disposition=inline&X-Amz-Security-Token=IQoJb3JpZ2lu…&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20241017T214313Z&X-Amz-SignedHeaders=host&X-Amz-Expires=300&X-Amz-Credential=ASIASHVRPOKPWCO2W6EQ%2F20241017%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Signature=15142ba…

Restore Backup on Heroku

Now that you have the presigned URL, use the Heroku pg:backups:restore command to restore your backup into your new Heroku Postgres database.

Use the heroku pg:backups:restore command and provide the presigned S3 URL for your backup in quotes, and the add-on name to restore your database to:

$ heroku pg:backups:restore 'AWS-S3-PRESIGNED-URL-IN-QUOTES' postgresql-silhouetted-05205 \
    --app psql-migration-from-aiven \
    --confirm psql-migration-from-aiven

Use Ctrl-C at any time to stop monitoring progress; the backup will continue restoring.
Use heroku pg:backups to check progress.
Stop a running restore with heroku pg:backups:cancel.

Starting restore of [AWS-S3-PRESIGNED-URL] to postgresql-silhouetted-05205... done
Restoring... done

Keep in mind with this command:

• When you paste in your AWS S3-signed URL, make sure to contain it within quotes.
• Provide the --app argument to tell Heroku which app and corresponding database you want to operate on.
• This command is destructive, requiring you to confirm it. If you don’t provide the --confirm argument, you’re asked to confirm the action before continuing.
• The restore process automatically reassigns ownership of all schemas and tables to the default Heroku credential. The command doesn’t import roles from the source Aiven Postgres database because the default Heroku database role doesn’t have permission to create Postgres roles.
• Make sure that all the extensions used in your Aiven Postgres database are supported on Heroku Postgres.

Migrate Any Custom Settings

Just as you saved your Aiven Postgres configurations to a file called /tmp/settings_postgres.csv, you can do the same for your Heroku Postgres configuration with the command:

$ heroku pg:psql --app psql-migration-from-aiven \
    -c "\copy (select * from pg_settings) to '/tmp/settings_heroku.csv' with (format csv, header true);"

Compare your Heroku Postgres settings with your Aiven Postgres settings. Find any configurations from your Aiven Postgres setup and reapply them to your Heroku Postgres instance.

Testing and Verifying a Successful Migration

We recommend testing to verify that data has migrated over successfully. Testing can include:

• Comparing table counts between the two databases.
• Comparing row counts for every table between the two databases.
• Comparing query results between the two databases.
• Running various acceptance tests on your new database to validate proper behavior and performance.
• Running the heroku pg:backups:info command to review the logs of your backup restore.

Connecting Existing Apps and Services

After verifying that the database migration was successful, point your existing apps and services to the new database.

Get Heroku Postgres Credentials

When you create the Heroku Postgres add-on, Heroku automatically configures a new environment variable called DATABASE_URL, which contains the connection string for the new database. Run the heroku config:get command to fetch the value of the config var:

$ heroku config:get DATABASE_URL --app psql-migration-from-aiven

postgres://uetkc4dpd6ip4h:pda698cf23811351f8822912c3c89710e2bbe5689c2b5cf25db66db394a2d7406@cbhk6rs82poqi7.cluster-czrs8kj4isg7.us-east-1.rds.amazonaws.com:5432/dds18t6dm96a15

You can also find your credentials with the heroku:pg:credentials command.

The Postgres connection string follows this format, so that you can parse the individual pieces:

postgres://DB_USERNAME:DB_PASSWORD@DB_HOST:DB_PORT/DB_NAME

Alternatively, you can obtain the connection string of your database through the dashboard.

Update Dependent Systems and Test

Update your existing systems to point to the Heroku Postgres database using its connection string. Test each system to make sure the connection is successful.

Now, you can also suspend your Aiven database service. Under the options in the top right of the database service main page, click Power off service.

Wrap-up

Now that your apps and services are pointing to Heroku Postgres and running as expected, you can close the maintenance window and restore full availability to your end users.

When you’re confident that the migration is successful and you no longer need your Aiven database, you can delete it completely. At the top right of the page, click Delete service and confirm you want to delete the database service.

With your migration complete, you can now enjoy the flexibility and low-cost convenience of Heroku Postgres. See our Heroku Postgres documentation for more information on using your database.