# Migrate Google Cloud SQL for PostgreSQL: Transactional workflows

Move PostgreSQL data from Google Cloud SQL for PostgreSQL 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 `pg_dump -Fc` through the Cloud SQL Auth Proxy or an authorized network. Not migrated automatically: Cloud SQL Auth Proxy/IAM authentication, high availability and PITR have no equivalent on the managed database.

## Cutover
Freeze writes with the user's go-ahead, take the final dump, restore, validate, redeploy with the managed DATABASE_URL, keep Cloud SQL until confirmed.

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

## Workflow Steps

1. **Inventory the source**  
   List what Google Cloud SQL for PostgreSQL provides beyond the component you are moving. Out of scope here: Cloud SQL Auth Proxy/IAM authentication, high availability and PITR have no equivalent on the managed database.

2. **Source step 1**  
   Take a logical backup with `pg_dump -Fc` through the Cloud SQL Auth Proxy or an authorized network.

3. **Source step 2**  
   Check the engine major version, extensions and flags the app depends on.

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.
   
   **Command:** `ample database create --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/transactional-workflows).

7. **Cut over**  
   Freeze writes with the user's go-ahead, take the final dump, restore, validate, redeploy with the managed DATABASE_URL, keep Cloud SQL 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.

## Limitations

- Documentation only: nothing is executed automatically and no execution binding is offered.
- The source-side procedure is documented from Google Cloud SQL for PostgreSQL'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: Cloud SQL Auth Proxy/IAM authentication, high availability and PITR 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.

## Success Checks

- **Destination app responds on its public URL**  
  **Type:** http_get  
  **Path:** /  
  **Expect:** ample canary express patterns

- **Transactional-workflows check from the destination example**  
  **Type:** http_get  
  **Path:** /p/transactional-workflows  
  **Expect:** see the pattern fixture checks

- **Data or object counts and checksums match the source**  
  **Type:** manual  
  **Expect:** operator comparison before cutover.

## Cost Estimate

- **Currency:** USD
- **Monthly Amount:** 10.0
- **Basis:** size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty

### Components
- **App server**: size: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0
- **Managed PostgreSQL database**: size: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0

**Note:** Destination always-on monthly price of the tested sizes; apps auto-pause when idle. Source costs are unknown to Ample.

## Example

- **Title:** Express pattern fixture (destination)  
  **Description:** Verified destination basis: transactional workflows.  
  **Source Reference:** tests/deploy-canaries/express-patterns

## Evidence Summary

- **Kind:** canary_run  
  **Summary:** Destination side verified: the Express pattern fixture deployed on Ample (npm install, npm run build --if-present, npm run start on the node-22 template) and its checks passed (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)). The source-side export from Google Cloud SQL for PostgreSQL is documented from the vendor's standard tooling and was not executed by this catalog's evidence.  
  **Observed At:** 2026-09-21T02:34:39Z  
  **Implementation Revision:** 1d28ae0-dirty (CLI 0.1.21)  
  **Expires At:** 2027-03-20T02:34:39Z  
  **Scope:** { "checks": ["/p/transactional-workflows"], "destinationOnly": true, "template": "node-22" }

## Last Verified At
2026-09-21T02:34:39Z

## Unknowns

- Region availability is unknown until a verified region fact is recorded.
- Compliance attestations are unknown; none are claimed.