CliqueSquare is a system for storing and querying large RDF graphs relying on Hadoop’s distributed file system (HDFS) and Hadoop’s MapReduce open-source implementation. It provides a novel partitioning and storage scheme that permits 1-level joins to be evaluated locally using efficient map-only joins. In addition, CliqueSquare is equipped with a unique optimization algorithm based on graphs and cliques capable of generating highly parallelizable flat query plans relying on n-ary equality joins.