From Legacy Systems

Map legacy schemas and behavior into QQQ incrementally with reconciliation and rollback.

Assess the existing application

Document tables and keys, validation and permissions, scheduled work, integrations, and users' critical workflows. Choose one bounded workflow for the first migration and record its expected outputs.

Map data explicitly

Use QTableMetaData and backend field names to map an existing schema. QQQ metadata does not perform a database migration automatically. For imports, use the configured application import process or typed insert/update actions; qctl import is not a QQQ 4.0 command.

Validate the transition

Reconcile record counts, keys, relationships, and representative values.

Compare authorization, validation failures, and side effects.

Test retries and duplicate handling for integrations and data sync.

Verify that users can complete the same workflow in the new interface.

Incremental replacement or parallel comparison can reduce cutover risk when responsibilities are clear. Avoid concurrent writers until ownership and conflict handling are defined. Restore a backup in a test environment and keep an application/data rollback procedure.

Continue with tables, processes, and deployment.