Schema migration readiness

This page describes how **Data Schema Consulting ** structures migration readiness work for clients moving between SQL engines, cloud managed databases, or major on-premise versions.

Phase 1 — Baseline capture

We collect authoritative DDL, sample row counts per table, and job schedules that touch the database. The goal is a single diagram that shows entities your finance and operations teams actually recognise, not only what developers remember.

Phase 2 — Constraint and dependency tracing

Foreign keys, triggers, and batch jobs often disagree. We list every enforcement path and mark which must be recreated in the target environment. Orphaned lookup tables and soft-delete flags get explicit call-outs because they break naive ETL assumptions.

Phase 3 — Target modelling

Together we decide naming conventions, surrogate key policy, and where historical data lands (archive schemas vs inline columns). We document rollback boundaries: what can revert in an hour versus what needs a forward-only plan.

Phase 4 — Validation harness

Before cut-over weekend, we draft row-count reconciliations, checksum queries on critical columns, and application smoke tests tied to schema versions. Your team runs them; we refine based on failures.

When to involve us

Bring us in early if regulators expect auditable lineage, if multiple vendors touch the same database, or if you have never migrated this workload without downtime. Request an assessment and we will suggest the lightest engagement that still de-risks your timeline.