Migrate Heroku Postgres: Transactional workflows

Move PostgreSQL data from Heroku Postgres to Ample, one component at a time. Destination verified on Ample: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events (history=2 conflict=rejected).

Source procedure: Take a logical backup with heroku pg:backups:capture and download it, or pg_dump -Fc against the credentials from heroku pg:credentials:url. Not migrated automatically: Heroku Postgres followers, forks, rollback (PITR) and dataclips have no equivalent on the managed database.

Cutover: Put the app in maintenance mode with the user's go-ahead, take the final backup, restore, validate, redeploy with the managed DATABASE_URL, keep the Heroku database until confirmed.

Rollback: Keep the source untouched until you confirm; nothing at the source is changed or deleted by this guide.

Prerequisites

• Authorized access to the Heroku Postgres source and its export tooling
• An inventory of every component in scope and out of scope
• A validated backup or copy before any cutover
• An Ample account token with servers:write, databases:read

Workflow Steps

1. Inventory the source
   List what Heroku Postgres provides beyond the component you are moving. Out of scope here: Heroku Postgres followers, forks, rollback (PITR) and dataclips have no equivalent on the managed database.

2. Source step 1
   Take a logical backup with heroku pg:backups:capture and download it, or pg_dump -Fc against the credentials from heroku pg:credentials:url.

3. Source step 2
   Check the Postgres major version and extensions against the managed engine (PostgreSQL 16).

4. Source step 3
   Restore into a scratch managed database first and compare row counts.

5. Provision and restore
   Deploy the app once so a managed PostgreSQL 16 database exists (or create one with ample database create --engine postgres), then restore the dump with pg_restore using its connection string; keep migrations idempotent.

6. Validate before cutover
   Run the app's own checks and, for data, compare counts and checksums; the example checks are the pattern self-tests (/p/transactional-workflows).

7. Cut over
   Put the app in maintenance mode with the user's go-ahead, take the final backup, restore, validate, redeploy with the managed DATABASE_URL, keep the Heroku database until confirmed.

8. Rollback
   Point DNS or configuration back to the source. The source was never modified; deletion is a separate, user-executed step after validation.

Examples

• Express pattern fixture (destination)
  Verified destination basis: transactional workflows.
  Source reference: tests/deploy-canaries/express-patterns.

Success Checks

• Destination app responds on its public URL: Expected ample canary express patterns.
• Transactional workflows check from the destination example: Expected see the pattern fixture checks.
• Data or object counts and checksums match the source: Expected operator comparison before cutover.

Limitations

• Documentation only: nothing is executed automatically and no execution binding is offered.
• The source-side procedure is documented from Heroku Postgres's standard tooling and was not executed in this catalog's evidence; the destination side was verified with the pattern fixture.
• No full source-product parity is claimed: Heroku Postgres followers, forks, rollback (PITR) and dataclips have no equivalent on the managed database.
• Verified on the node-22 template at s-1vcpu-1gb; region, compliance and request-duration limits are unknown.
• Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures on the managed side are not verified beyond the pattern checks.