Transaction management across data stores

Companies have evolved from a world where they only had SQL databases to a world where they use different kinds of data stores, such as key­value data stores, document­oriented data stores and graph databases. The reason why they have started to introduce this diversity of persistency models is because different NoSQL technologies bring different data models with associated query languages and/or APIs. However, they are confronted now with a problem in which they have the data scattered across different data stores. This problem lies in that when a business action requires to update the data, the data reside in different data stores, and they are subject to inconsistencies in the event of failure and/or concurrent access. These inconsistencies appear due to the lack of transactional consistency that was guaranteed in traditional SQL databases but is not guaranteed either within the NoSQL data stores or across data stores and databases. CoherentPaaS comes to remedy this need. CoherentPaaS provides an ultra­scalable transactional management layer that can be integrated with any data store with multi­ versioning capabilities. The layer has been integrated with six different data stores, three NoSQL data stores and three SQL­like databases. In this paper, we describe this generic ultra­scalable transactional management layer and focus on its API and how it can be integrated in different ways with different data stores and databases.