Related, but there is also no replacement for querying over prod data to figure out the shape of your data. When you work with old systems, it is important to v

Related, but there is also no replacement for querying over prod data to figure out the shape of your data. When you work with old systems, it is important to validate your assumptions by looking at what your prod data actually is. Don't just assume all data in some column is all lowercase, write a query looking for data with uppercase characters (or number of rows with uppercase characters if said column is PII).