HyperDex is the next generation key-value store with a wide array of features. HyperDex may be a good fit for you if your application needs to:

Perform atomic transactions over multiple objects, in a fast, scalable NoSQL data store.
Store rich datatypes such as strings, integers, floats, lists, maps, and sets.
Search and retrieve objects efficiently by secondary attributes.
Ensure that your data is up to date at all times with strong consistency guarantees.
Protect your data against a configurable number of simultaneous failures.
HyperDex's key features -- namely its rich API, strong consistency, and fault tolerance -- provide strong guarantees to applications that are not matched by other NoSQL systems.

Of course, if the data is rarely modified, or it has no consistency or fault-tolerance requirements, HyperDex may not be for called for, though it still outperforms other NoSQL stores that provide weaker guarantees.