- published: 16 May 2012
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Apache Cassandra is an open source distributed database management system. It is an Apache Software Foundation top-level project designed to handle very large amounts of data spread out across many commodity servers while providing a highly available service with no single point of failure. It is a NoSQL solution that was initially developed by Facebook and powered their Inbox Search feature until late 2010. Jeff Hammerbacher, who led the Facebook Data team at the time, has described Cassandra as a BigTable data model running on an Amazon Dynamo-like infrastructure.
Cassandra provides a structured key-value store with tunable consistency. Keys map to multiple values, which are grouped into column families. The column families are fixed when a Cassandra database is created, but columns can be added to a family at any time. Furthermore, columns are added only to specified keys, so different keys can have different numbers of columns in any given family.
The values from a column family for each key are stored together. This makes Cassandra a hybrid data management system between a column-oriented DBMS and a row-oriented store. Additional features include: using the BigTable way of modeling, eventual consistency, and the Gossip protocol, a master-master way of serving read and write requests inspired by Amazon's Dynamo.
In Greek mythology, Cassandra (Greek Κασσάνδρα, also Κασάνδρα, also known as Alexandra) was the daughter of King Priam and Queen Hecuba of Troy. Her beauty caused Apollo to grant her the gift of prophecy. In an alternative version, she spent a night at Apollo's temple, at which time the temple snakes licked her ears clean so that she was able to hear the future (this is a recurring theme in Greek mythology, though sometimes it brings an ability to understand the language of animals rather than an ability to know the future). When she did not return his love, Apollo placed a curse on her so that no one would ever believe her predictions. She is a figure both of the epic tradition and of tragedy, where her combination of deep understanding and powerlessness exemplify the ironic condition of humankind.
Cassandra was the daughter of King Priam and Queen Hecuba and the twin sister of Helenus. She was said to have had red hair kept in curls, blue eyes,and fair skin and she was very beautiful, intelligent, charming, desirable, elegant, friendly, and gentle, but she was considered to be insane. Cassandra was described as the "second most beautiful woman in the world." Her beauty was even compared to that of Aphrodite and Helen of Troy.