Thank you for your replies. So, the best way to test the ETL migration is through manual testing. I mean by executing the sql queries (based on the test cases developed) to ensure about the data quality in the old database and new database and comparing the results. For data quantityalso the sql queries can be used.
I have also searched for the data validation tools but could not find what I am loooking for. There are some tools which do the data validation like having a phone number in certain format etc but not comparing the data in two databases (legacy vs new db with different data structures).
