We've been recently witnessing information explosion, which is closely related to data explosion. We now have applications that need to write to and read from persistent storage at a rate of millions of objects per hour. This scalability issue has paved the way for non-relational or NoSQL databases. These systems offer flexibility and speed at scale, and thus data-intensive applications have been choosing these systems over relational databases as the relational ones aren't able to cope up with massive amounts of data increasing at the current pace.