Apache Cassandra is an open source, decentralized; highly available, fault-tolerant, distributed, column-oriented, elastically scalable database that bases its distribution design on its data model and Amazon’s Dynamo on Google’s Bigtable. It is capable enough to store hundreds of terabytes of data. \n\nCassandra originated at Facebook in 2007 to solve that company’s inbox search problem, in which they had to deal with large volumes of data in a way that was difficult to scale with traditional methods. Specifically, the team had requirements to handle huge volumes of data in the form of message copies, reverse indices of messages, and many random reads and many simultaneous random writes. For developers and administrators coming from the relational world, the Cassandra data model can be very difficult to understand initially. Some terms, such as “keyspace,” are completely new, and some, such as “column,” exist in both worlds but have different meanings. It can also be confusing if you’re trying to sort through the Dynamo or Bigtable source papers, because although Cassandra may be based on them, it has its own model.