The blooming of different cloud data management infrastructures, specialized for different kinds of data and tasks, has led to a wide diversification of DBMS interfaces and the loss of a common programming paradigm. The CoherentPaaS project addresses this problem, by providing a common programming language and holistic coherence across different cloud data stores. In this talk, I will present the design of a Cloud Multi-datastore Query Language (CloudMdsQL), and its query engine. CloudMdsQL is a functional SQL-like language, capable of querying multiple heterogeneous data stores (relational and NoSQL) within a single query that may contain embedded invocations to each data store’s native query interface. Thus, CloudMdsQL unifies a quite diverse set of data management technologies while preserving the expressivity of their local query languages. Our experimental validation, with three data stores (graph, document and relational) and representative queries, shows that CloudMdsQL satisfies the five important requirements for a cloud multidatabase query language.