Recent years have seen a resurgence of interest in Datalog from both the industry and research community. Datalog is a declarative query language that extends relational algebra with recursion. It is used to express a wide spectrum of modern data management tasks such as data integration, declarative networking, graph analysis, business analytics, and program analysis. The result of this long line of research is a plethora of Datalog engines that support different variants of Datalog, and have different technical specifications and capabilities. In this monograph, the authors provide an...