The migration validated clean, and three of these were never compared
A migration is a day from cutover. DMS data validation has been on since the full load, the task shows no failures, and the sign-off email says "validation passed, zero mismatches".
Six objects were in scope. Validation compares rows one by one where it can, and where it cannot it says so quietly, in a per-table state nobody opened.
Tap every object that the validation report is not evidence for.
!Three weeks after cutover, a finance query returns numbers that never existed on the source. The migration was signed off on a validation report with zero failures, and the report was accurate — it simply did not cover everything anybody thought it did."Zero failures" and "everything matched" are different claims. A table that was never compared cannot fail.
Boundaries, outermost first: In scope for the migration: price_list (PK: sku), events (append-only, no PK), customers (PK masked in the mapping), audit_log (PK: audit_id), v_daily_summary (a view over three tables), orders (PK: order_id) This diagram draws no connections between its components.
Tap every component that is wrong.