There are four basic types of NoSQL databases:

Document databases, such as MongoDB, pair each key with a complex data structure known as a document. Documents can contain many different key-value pairs, or key-array pairs, or even nested documents.

Graph stores are used to store information about networks of data, such as social connections. Graph stores include Neo4J and Giraph.

Key-value stores are the simplest NoSQL databases. Every single item in the database is stored as an attribute name (or key), together with its value. Examples of key-value stores are Riak and Berkeley DB. Some key-value stores—such as Redis—allow each value to have a type which adds functionality.

Wide-column stores such as Cassandra and HBase are optimized for queries over large datasets, and store columns of data together, instead of rows.

Features and Benefits of NoSQL

• Provides lower cost, high-availability options
• Address large volumes of rapidly changing structured, semi-structured and unstructured data
• Organize data as a structured query language (SQL) or into objects, key/value pairs or tuples
• Support massive numbers of concurrent users (from hundreds to millions)
• Deliver highly responsive experiences to a globally distributed user base
• Adapt quickly to changing requirements with frequent updates and new features