This is not really accurate. Some NoSQL solutions, such as Memcached, MemcacheDB, and REDIS are key-value stores, i.e. hash tables. Other solutions, such as C

This is not really accurate. Some NoSQL solutions, such as Memcached, MemcacheDB, and REDIS are key-value stores, i.e. hash tables. Other solutions, such as Cassandra, MongoDB, and CouchDB provide richer semantics that make it possible to perform efficient range queries and map-reduce queries. Cassandra and MongoDB both use indices to improve query performance. One of the primary advantages of the various NoSQL solutions is that they make it easy to scale horizontally, i.e. to add capacity by simply adding another host machine. This is in contrast to traditional relational databases, which are typically hard to scale horizontally.