1. We can simply extract the man with age below 45 or else from big data. It's impossible to extract if we just use one flat files
  2. The database can scale vertically instead of horizontally effectively
  3. It's impossible if in one example the age is int type, while the other is string type
  4. Data is less redundant, because it represent how it is
  5. Not a good reason to choose relational database.