Cloud stores have become the storage of choice for a large variety of big data producers, consumers, and managers (e.g., Twitter, Facebook, Google, Amazon, etc.) For many modern Big Data applications, RDBMSs were found lacking, particularly with respect to scalability (in terms of number of data items, users, operations per second, etc.), despite valiant e orts (e.g., sharding, memory caches, partial denormalization, etc.). To fill this gap, two complementary technologies emerged: NoSQL databases and the MapReduce framework. Interestingly, even traditional key RDBMS players, such as Oracle, are now focusing on NoSQL products coupled with MapReduce platforms.