NimbusDB's software is still at an "early alpha" stage, and Starkey didn't provide a delivery date Thursday. The company expects to give the software away free "for the first couple of nodes," and customers can pay for additional capacity, he said. Its product is delivered as software, rather than a service, but not open-source software, Starkey said.

Xeround aims to solve similar problems as NimbusDB but with a hosted MySQL service that's been in beta with about 2,000 customers and went into general availability last week, said CEO Razi Sharir. It, too, wants to offer the elasticity of the cloud with the familiarity of SQL coding.

"We're a distributed database that runs in-memory, that splits across multiple virtual nodes and multiple data centers and serves many customers at the same time," he said. "The scaling and the elasticity are handled by our service automatically."

Xeround is designed for transactional workloads, and the "sweet spot" for its database is between 2GB and 50GB, Sharir said.

Its service is available in Europe and the U.S., hosted by cloud providers including Amazon and Rackspace. While Xeround is "cloud agnostic," cloud database customers in general need to run their applications and database in the same data center, or close to each other, for performance reasons.