See
http://www.datasciencecentral.com/profiles/blogs/ten-top-nosql-databases
What will it take before Cache begins to appear on (or at the very least be considered for) such lists?
A key-value data model, or key-value store, is a data storage paradigm designed for storing, retrieving, and managing associative arrays, a data structure more commonly known today as a dictionary or hash. Dictionaries contain a collection of objects, or records, which in turn have many different fields within them, each containing data InterSystems Data platform supports key-value concept of data management.