Apache Cassandra

MongoDB is better than other SQL databases because it allows a highly flexible and scalable document structure . For example: One data document in MongoDB can have five columns and the other one in the same collection can have ten columns.

There are many popular NoSQL options available, like Apache Cassandra, MongoDB, Redis, and Couchbase . Well, it totally depends upon your project; if it’s using Cassandra, then you probably need to learn Cassandra, and if it is using MongoDB, then you probably need to learn MongoDB.

SQL databases are better for multi-row transactions, while NoSQL is better for unstructured data like documents or JSON . SQL databases are also commonly used for legacy systems that were built around a relational structure.

ScyllaDB : A Monstrously Fast and Scalable NoSQL Database.