First came SQL, then NoSQL, and now there’s another addition to the SQL nomenclature: NewSQL.

The latest addition comes from the research firm The 451 Group, which published a report last month entitled How will the database incumbents respond to NoSQL and NewSQL?

“NewSQL is our shorthand for the various new scalable/high performance SQL database vendors,” explained 451 Analyst Matthew Aslett. “We previously referred to these products as ‘ScalableSQL’ to differentiate them from the incumbent relational database products. Since this implies horizontal scalability, which is not necessarily a feature of all the products, we adopted the term ‘NewSQL’ in the new report.”

Aslett identified three major product areas in the space:

• NoSQL databases — designed to meet the scalability requirements of distributed architectures, and/or schema-less data management requirements
• NewSQL databases — designed to meet the requirements of distributed architectures or to improve performance such that horizontal scalability is no longer needed
• Data grid/cache products — designed to store data in memory to increase application and database performance

Aslett emphasized that the term NewSQL, like NoSQL, should not be taken too literally.

“The new thing about NewSQL is the vendor, not the SQL,” he said. “Like NoSQL, NewSQL is used to describe a loosely-affiliated group of companies.”

What the NewSQL companies have in common is their development of new relational database products and services designed to bring the benefits of the relational model to distributed architectures, he said.

So which companies does the 451Group consider to be NewSQL vendors?

In the first group the firm includes: Akiban, Clustrix, CodeFutures, Drizzle, GeniDB, MySQL Cluster with NDB, MySQL with HandlerSocket, NimbusDB, RethinkDB, ScalArc, Schooner, Translattice and VoltDB.

The second group, which 451 classifies as NewSQL-as-a-service, includes Amazon Relational Database Service, Database.com, FathomDB, Microsoft SQL Azure, and Xeround.

Clearly there is the potential for NewSQL to overlap with NoSQL. For example, said Aslett, it remains to be seen whether RethinkDB will be delivered as a NoSQL key value store for memcached or a NewSQL storage engine for MySQL.

“NewSQL is not about attempting to re-define the database market using our own term, but it is useful to broadly categorize the various emerging database products at this particular point in time,” said Aslett.

NewSQL as Cloud Database

In addition to the differentiators Aslett outlines between the various NewSQL solutions, Xeround’s CEO Razi Sharir adds some more.

“Aslett did not use the term ‘cloud database,'” said Sharir. “I would maintain that a cloud-database is one that’s built from the ground-up optimally for the cloud environment, providing ‘natural’ and unlimited elasticity by using only cloud resources.

Tools, applications and solutions used in a traditional on-premise and/or hosted environment simply don’t cut it anymore on the uniquely distributed environment of the cloud, said Sharir.

“To take advantage of the benefits of the cloud, a cloud-enabled solution needs to be designed, built and deployed in a cloud fashion, so that the core technology relies on virtualized resources — with the cloud as an abstract management layer on top,” he said.

Simply running a traditional hosted database in a VM is not sufficient for providing a database service that’s optimal for the cloud, he added.

Sharir claimed Xeround is the only NewSQL solution to offer a native cloud Database-as-a-Service, and that the solution combines the best of both worlds: NoSQL and SQL.

“Underneath the hood, we’re a fully virtualized cloud NoSQL database (DHT + distributed b-tree indexes and object store,) and on the forefront, we have a customized parser that enables us to offer various database flavors, which currently expose MySQL via the storage engine API,” he said.

What lies ahead for SQL, NoSQL and NewSQL?

“The lines are blurring to the point where we expect the terms NoSQL and NewSQL will become irrelevant as the focus turns to specific use cases,” said Aslett.