DBAs typically normalize data to improve the performance of their relational databases. Normalization organizes data into separate tables that each store data for one type of entity (e.g., customers, orders, products) or that provide the same physical data storage for different logical entities (e.g., shipping address, billing address). In the normalization, foreign keys associate values in one table with values in another table. In contrast, an XML document is rarely normalized because XML typi...