## Migrate Neon database: JSON document metadata

### Summary
Move PostgreSQL data from Neon database 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 `pg_dump -Fc` from the primary branch. Not migrated automatically: Neon branching, autoscaling and scale-to-zero semantics have no equivalent; the managed database is one instance per app.  
- **Cutover**: Freeze writes at the source with the user's go-ahead, take the final dump, restore, validate, redeploy the app with the managed DATABASE_URL, keep the Neon project until confirmed.  
- **Rollback**: keep the source untouched until you confirm; nothing at the source is changed or deleted by this guide.

### Workload
JSON document metadata

### Migration Source
Neon database

### Execution Status
unbound

### Prerequisites
- Authorized access to the Neon database 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 Neon database provides beyond the component you are moving. Out of scope here: Neon branching, autoscaling and scale-to-zero semantics have no equivalent; the managed database is one instance per app.  
2. **Source step 1**  
   Take a logical backup with `pg_dump -Fc` from the primary branch.  
3. **Source step 2**  
   Check the Postgres major version and extensions in use 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.  
   ```bash
   ample database create --name <your-db-name> --engine postgres
   ```  
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**  
   Freeze writes at the source with the user's go-ahead, take the final dump, restore, validate, redeploy the app with the managed DATABASE_URL, keep the Neon project 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.

### Success Checks
- **Destination app responds on its public URL**  
   - kind: http_get  
   - path: /  
   - expect: ample canary express patterns  
- **json-document-metadata check from the destination example**  
   - kind: http_get  
   - path: /p/json-document-metadata  
   - expect: see the pattern fixture checks  
- **Data or object counts and checksums match the source**  
   - kind: manual  
   - expect: operator comparison before cutover.

### Limitations
- Documentation only: nothing is executed automatically and no execution binding is offered.  
- The source-side procedure is documented from Neon database'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: Neon branching, autoscaling and scale-to-zero semantics have no equivalent; the managed database is one instance per app.  
- 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.