MemSQL, The Real-Time Analytics Platform
For a great overview see the video embedded below and at this link:
MemSQL's real-time analytics platform is built on the world's fastest, most scalable in-memory database, capable of simultaneously handling real-time transactions and analytic workloads. MemSQL unleashes the full potential of Big Data by consuming and returning data instantly.
MemSQL is designed to consume millions of events per second and simultaneously query the data, delivering a complete Big Data solution for both real-time and historical data.
The MemSQL database scales incrementally across commodity hardware, so you can build the system that meets your needs in terms of both data volume and query performance.
MemSQL leverages multi-version concurrency control and lock-free data structures. Neither writes nor reads block one another, so teams can query MemSQL even as real-time data enters the system.
For more information see http://memsql.com