Cassandra (database)

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 powers their Inbox Search feature. Jeff Hammerbacher, who led the Facebook Data team at the time, has described Cassandra as a BigTable data model running on a Amazon Dynamo-like infrastructure.

Cassandra provides a structured key-value store with eventual 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, making Cassandra a hybrid between a column-oriented DBMS and a row-oriented store.

Prominent Users

   * Facebook uses Cassandra to power Inbox Search, with over 200 nodes deployed.
   * Digg, the largest social news website, annouced on Sep 9th, 2009 that it is rolling out its use of Cassandra.
   * Twitter is working towards replacing storage of all tweets with Cassandra.
   * Rackspace is known to use Cassandra internally
   * Cisco's WebEx uses Cassandra to store user feed and activity in near real time
   * IBM has done research in building a scalable email system based on Cassandra

Read more: Wikipedia
Ofiicial site: Cassandra

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