Cassandra

Apache Cassandra®, developed and supported by the Apache Project, is a FOSS database management system for NoSQL databases. The application was originally developed at Facebook to support the Inbox Search feature and was released as an open-source project in July 2008. In 2009, Cassandra became part of the Apache Incubator Project, and in 2010, it became an Apache Top-Level Project.

Cassandra’s main feature is distributing data across a large number of servers, which not only guarantees high availability but also eliminates any single point of failure. Cassandra’s cluster concept is also “masterless,” meaning it operates without a specific controlling server, instead functioning as a collaborative network of all servers that are part of the cluster. One of the key features of this dense network is replication across different data centers.

Instead of typically using SQL as a query language, Cassandra provides CQL, the Cassandra Query Language. This adds an additional layer of abstraction between the database and the user and includes many commands specifically tailored for Cassandra and cluster applications. As a Java-based system, Cassandra can be monitored using Java Management Extensions. For example, Nodetool can be used as a management system to add or remove machines from the cluster.