Types of NoSQL Databases

Since "NoSQL" just means non-relational and not SQL, there are many different ways to implement NoSQL technology. Generally, NoSQL databases include the following families

• 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-:Oracle BDB,AmazonSimpleDB,Riak

• Document databases 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.  Examples -: MongoDB,CouchDB

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

• Graph stores are used to store information about networks, such as social connections.    Examples –: Graph stores include Neo4J and HyperGraphDB.