# Migrate Google Cloud SQL for PostgreSQL: Relational records

Move PostgreSQL data from Google Cloud SQL for PostgreSQL to Ample, one component at a time. Destination verified on Ample: a workspace-scoped table, an explicit state machine (draft to review to published) that rejects invalid transitions, and a cross-workspace read that returns nothing (transitions=true isolation=true).

## 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 <database-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/relational-records).

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.

## Examples
- **Express pattern fixture (destination)**  
  Verified destination basis: relational records.
  Source Ref: `tests/deploy-canaries/express-patterns`

## Success Checks
- Destination app responds on its public URL (/)
  - Expect: ample canary express patterns
- Relational records check from the destination example (/p/relational-records)
  - Expect: see the pattern fixture checks
- Data or object counts and checksums match the source
  - 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 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.

## Cost Estimate
- **Currency**: USD
- **Monthly Amount**: 10.0
- **Components**:
  1. App Server: Size - s-1vcpu-1gb, Quantity - 1.0, Monthly Amount - 5.0
  2. Managed PostgreSQL Database: Size - s-1vcpu-1gb, Quantity - 1.0, Monthly Amount - 5.0
- Note: Destination always-on monthly price of the tested sizes; apps auto-pause when idle. Source costs are unknown to Ample.