PostgreSQL, the NoSQL Database

By Reuven Lerner

One of the most interesting trends in the computer world during the past
few years has been the rapid growth of NoSQL databases. The term may
be accurate, in that NoSQL databases don’t use SQL in order to store
and retrieve data, but that’s about where the commonalities end. NoSQL
databases range from key-value stores to columnar databases to
document databases to graph databases.

From: Linux Journal