About Apache Cassandra

Documentation for developers and administrators on configuring, and using the features and capabilities of Apache Cassandra.

Apache Cassandra™ is a massively scalable open source NoSQL database. Cassandra is perfect for managing large amounts of structured, semi-structured, and unstructured data across multiple datacenters and the cloud. Cassandra delivers continuous availability, linear scalability, and operational simplicity across many commodity servers with no single point of failure, along with a powerful dynamic data model designed for maximum flexibility and fast response times.

The latest version of Apache Cassandra™ 2.1 is 2.1.21.

How does Cassandra work?

Cassandra’s built-for-scale architecture means that it is capable of handling petabytes of information and thousands of concurrent users/operations per second.


Cassandra is a partitioned row store database	Cassandra's architecture allows any authorized user to connect to any node in any datacenter and access data using the CQL language. For ease of use, CQL uses a similar syntax to SQL. The most basic way to interact with Cassandra is using the CQL shell, cqlsh. Using cqlsh, you can create keyspaces and tables, insert and query tables, plus much more. If you prefer a graphical tool, you can use DataStax DevCenter. For production, DataStax supplies a number of drivers so that CQL statements can be passed from client to cluster and back.
Automatic data distribution	Cassandra provides automatic data distribution across all nodes that participate in a ring or database cluster. There is nothing programmatic that a developer or administrator needs to do or code to distribute data across a cluster because data is transparently partitioned across all nodes in a cluster.
Built-in and customizable replication	Cassandra also provides built-in and customizable replication, which stores redundant copies of data across nodes that participate in a Cassandra ring. This means that if any node in a cluster goes down, one or more copies of that node’s data is available on other machines in the cluster. Replication can be configured to work across one datacenter, many datacenters, and multiple cloud availability zones.
Cassandra supplies linear scalability	Cassandra supplies linear scalability, meaning that capacity may be easily added simply by adding new nodes online. For example, if 2 nodes can handle 100,000 transactions per second, 4 nodes will support 200,000 transactions/sec and 8 nodes will tackle 400,000 transactions/sec: