Last updated July 26, 2024

Forking creates a new database containing a snapshot of an existing database at the current point in time. Unlike follower databases, forks don’t stay up to date with the parent database and you can write to them. Forks don’t affect the performance of the parent database.

Use Cases

Forked databases provide a risk-free way of working with your production data and schema. For example, you can use them to test new schema migrations or to load test your application on a different database plan. They’re also valuable as snapshots of your data at a particular point in time for later analysis or forensics.

Create a Fork

You can create forks on any Standard, Premium, Private, or Shield database that isn’t a follower.

Forks don’t have to be on the same database plan as the parent database. Forks can be on any plan but must have enough disk space to contain the data from the parent database.

Preparing a fork can take anywhere from several minutes to several hours, depending on the size of your dataset.

Create Using the CLI

You can create forks using the Heroku CLI with the heroku addons:create command. Provision a new database add-on with the --fork flag. Supply the flag with one of the following:

• The config var name of the database on the same app
• The name of the database add-on
• The full URL of any Heroku Postgres database
• An argument in the form of appname::HEROKU_POSTGRESQL_COLOR_URL. This allows you to create a fork of a database that is attached to another app.

$ heroku addons:create heroku-postgresql:standard-0 --fork HEROKU_POSTGRESQL_CHARCOAL_URL --app example-app

$ heroku addons:create heroku-postgresql:standard-0 --app example-app -- --fork HEROKU_POSTGRESQL_CHARCOAL_URL
Adding heroku-postgresql:standard-0 on example-app... done, v71 ($50/mo)
Attached as HEROKU_POSTGRESQL_SILVER_URL
Database will become available after it completes forking
Use `heroku pg:wait` to track status

The heroku pg:wait command outputs the provisioning status of any new databases. Use it to determine when the fork is up to date.

$ heroku pg:wait --app example-app
Waiting for database HEROKU_POSTGRESQL_SILVER_URL... available

Create Using the Heroku Data Dashboard

You can also create forks through the web dashboard:

1. Go to data.heroku.com.
2. Use the search and select the database you want to create a fork from.
3. Click the Settings tab.
4. Click Fork Database....
5. Choose the plan for the fork. Review the Create a Fork section for notes on selecting a plan size.
6. Click Fork Database.

The dashboard shows the status of the forked database and updates when the provisioning is complete.

Fork Fast Option

You can create forks faster via the CLI with the --fast flag. This option is useful if no major changes, such as schema migrations or large data imports, occurred in your database in the last 30 hours.

$ heroku addons:create heroku-postgresql:standard-4 --fork HEROKU_POSTGRESQL_CHARCOAL --fast --app example-app

$ heroku addons:create heroku-postgresql:standard-4 --app example-app -- --fork HEROKU_POSTGRESQL_CHARCOAL --fast
Adding heroku-postgresql:standard-4 on dashboard... done, v1022 ($1200/mo)
Attached as HEROKU_POSTGRESQL_BLUE_URL
Fork will contain data from 5/26/2021 at 13:56 UTC (about 16 hours old)
To create a fork with up-to-date data, exclude the `--fast` flag.
Database will become available after it completes forking
Use `heroku pg:wait` to track status.
Use `heroku addons:docs heroku-postgresql` to view documentation

Delete a Fork

Delete Using the CLI

Deprovision a fork using heroku addons:destroy:

$ heroku addons:destroy HEROKU_POSTGRESQL_SILVER --app example-app
!    WARNING: Destructive Action
!    This command will affect the app: example-app
!    To proceed, type "example-app" or re-run this command with --confirm example-app

Delete Using the Heroku Data Dashboard

1. Go to data.heroku.com.
2. Use the search and select the fork database you want to delete.
3. Click the Settings tab.
4. Click Delete Database....
5. Type in the name of your app to confirm.
6. Click Delete Database.