While MongoDB has been the most popular NoSQL database over the past few years, it appears Cassandra is most popular over the past six months. Many assert that Cassandra has superior scalability, better data management features, is faster and MongoDB has more moving parts and complexity to cause problems. Others claim Cassandra is difficult to learn and requires a major re-thinking of the data model and MongoDB is easier to use for developers with faster speed of development.

Differences between NoSQL and NewSQL databases are much larger than between SQL databases and thus determining which database architecture to use for a specific project is critical.