[ uh-pach-ee kuh-san-dra] n. Apache Cassandra is an open source, distributed and decentralized/distributed storage system (database), for managing very large amounts of structured data spread out across the world. It provides highly available service with no single point of failure. It is a type of NoSQL database.
By design, NoSQL databases are lightweight, open-source, non-relational, and largely distributed. Counted among their strengths are horizontal scalability, distributed architectures, and a flexible approach to schema definition.
NoSQL databases enable rapid, ad-hoc organization and analysis of extremely high-volume, disparate data types. Cassandra is among the NoSQL databases that have addressed the constraints of previous data management technologies, such as SQL databases.