NoSQL data stores have emerged in last years as a solution to provide scalability and flexibility in data modelling for operational databases. These data stores have proven that they are better suited for some kinds of problems than relational databases. In order to scale, they relaxed the properties provided by relational databases, mainly transactions. However, transactional semantics is still needed by most applications. In this paper we describe how CoherentPaaS provides scalable holistic transactions across SQL and NoSQL data stores such as document-oriented data stores, key-value data stores and graph databases.