# Migrate Heroku Postgres: JSON document metadata

Move PostgreSQL data from Heroku Postgres to Ample, one component at a time. Destination verified on Ample: a jsonb column with a GIN index queried by path and containment, with an aggregate over matching documents (json=ok). 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.

## Representative Queries
- Migrate Heroku Postgres: JSON document metadata
- Where can I host JSON document metadata?
- I need a component-scoped export/import or reconfiguration procedure for JSON document metadata, with compatibility checks, verification and rollback.

## 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

## Resource Requirements
- Primitive: Postgres

## Infrastructure Requirements
- **Postgres**: Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.

## 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/json-document-metadata).
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.

## Cost Estimate
- **Currency**: USD
- **Monthly Amount**: 10.0
- **Note**: Destination always-on monthly price of the tested sizes; apps auto-pause when idle. Source costs are unknown to Ample.
  - **Components**:
    - App server: s-1vcpu-1gb
    - Managed PostgreSQL database: s-1vcpu-1gb

## 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. 
- Verified on the node-22 template at s-1vcpu-1gb; region, compliance and request-duration limits are unknown.

## Success Checks
- Destination app responds on its public URL
- json-document-metadata check from the destination example
- Data or object counts and checksums match the source

## Examples
- **Express pattern fixture (destination)**: Verified destination basis: JSON document metadata.