MNJLarge migrations are risky because row counts matching is not enough; you also need to prove that keys, relationships, null handling, and business-critical measures survived the move.
You are migrating a large dataset from an acquired company's database into an existing PostgreSQL-based platform such as Broadcom Clarity or DX Operational Intelligence. Explain how you would ensure data integrity before, during, and after the migration. Your answer should cover how you would validate record completeness, detect duplicates, reconcile aggregates between source and target, and protect referential integrity while loading data.
Go beyond generic statements like “run tests” or “compare counts.” The interviewer expects a practical SQL-focused answer that references reconciliation queries, staging patterns, transaction safety, and how you would investigate mismatches at row and aggregate levels.
