Teams often validate ETL reliability by comparing daily record counts in source systems against warehouse tables. This is a common first-line data quality check because it quickly surfaces missing loads, duplicate loads, and date-partition issues.
Explain how you would design a process to compare daily source counts against warehouse counts. Your answer should cover:
The interviewer is looking for a practical design explanation, not a full production implementation. Focus on a simple, reliable reconciliation pattern using SQL aggregations, clear assumptions, and operational considerations such as scheduling, idempotency, and alerting.