Some months ago I had a discussion with NoSQL creator, Carlo Strozzi, regarding the databases. I should admit, I am an SQL fan! It's hot having the same language, no matter which platform or database engine is used. He underlined the fact that most SQL engines lack of flexibility and waste system resources (memory and disk space) because of their multi-platform environment (such as Oracle, DB2, Informix, etc.). He suggested I have a look at the white paper that inspired him: “The UNIX Shell As a Fourth Generation Language” by Evan Schaffer (firstname.lastname@example.org) and Mike Wolf (email@example.com). Quoting from the above paper:
For almost a year now, the idea of " NoSQL " has been spreading due to the demand for relational database alternatives. Maybe the biggest motivation behind NoSQL is scalability. Relational databases don't lend themselves well to the kind of horizontal scalability that's required for large-scale social networking or cloud applications, and ORMs can abstract away impedance mismatch only so much. In other cases, companies just don't need as many of the complex features and rigid schemas provided by relational databases. Most people are not suggesting that we all ditch the RDBMS, in fact, many companies don't really need to switch.
Relational databases have ruled data storage for more than 30 years, but the growing popularity of schemaless (or NoSQL) databases suggests that change is underway. While the RDBMS provides a rock-solid foundation for storing data in traditional client-server architectures, it doesn't easily (or cheaply) scale to multiple nodes. In the era of highly scalable Web apps like Facebook and Twitter, that's a very unfortunate weakness to have. Whereas earlier alternatives to the relational database (remember object-oriented databases?)