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Knowledge Graph Construction with R2RML and RML: An ETL System-based Overview

Knowledge graphs have proven to be a powerful technology to integrate and structure the myriad of data available nowadays. The semantic web community has actively worked on data integration systems, providing an important set of engines and mapping languages to facilitate the construction of knowledge graphs. Despite these important efforts, there is a lack of objective evaluations of the capabilities of these engines in terms of performance, scalability, and conformance with mapping specifications. In this work, we conduct such evaluation considering several R2RML and RML processors to identify their strengths and weaknesses. We (i) perform a qualitative analysis of the distinctive features of each engine, (ii) examine their conformance with the mapping language specification they support, and (iii) assess their performance and scalability using the GTFS-Madrid-Bench benchmark.