Why does it happen? Why do we limit ourselves to relational databases only? Of course, there exists a set of situations in which relational databases are the best tool for the job, but – conversely – there exists a set of situations where relational database is a very inferior tool. Each type of tool has its purpose, limitations, and applications in which the tool will be the best. The important thing is not to look at the application from the point of view of a database only. We need to look at the ap...