Discuss the most distinct feature of each of the following real-life databases:

A supermarket chain issues loyalty cards to their customers. The card enables the supermarket chain to monitor purchases made by each individual customer. Each customer transaction consists of a number of purchased items that are scanned into the database via barcode readers. Each day, a typical store processes thousands of customer transactions. The stores of the supermarket chain are open for most days during a year. There are hundreds of stores throughout the country.