Database Migration Testing Using Source-to-Target Comparison

Abstract

Database migration testing using source-to-target comparison is an important activity for ensuring that data transferred from an old system to a new database remains complete, accurate, and usable. In enterprise environments, migration errors may occur due to incorrect field mapping, data type mismatch, missing records, duplicate values, transformation mistakes, constraint violations, or incomplete extraction. This article discusses how structured source-to-target comparison helps verify row counts, field values, key relationships, data formats, control totals, and business rule alignment after migration. It explains the role of mapping documents, reconciliation reports, validation queries, exception logs, sample checks, and defect records in improving migration reliability. The article also highlights common challenges such as inconsistent legacy data, incomplete metadata, changed business codes, large data volumes, and difficulty validating transformed fields. A structured migration testing approach is presented to improve data integrity, reduce migration risk, support audit readiness, and strengthen confidence in the new database environment. The study concludes that effective source-to-target comparison improves migration accuracy, reduces post-migration defects, and supports successful enterprise database modernization.