Section: New Results

Massively Distributed Data Management Systems

One of the main results of the year is the publication of the full paper [15] and demonstration [14] on CliqueSquare in the highly prestigious IEEE Conference on Data Engineering (ICDE). CliqueSquare has also been released in open source in 2014 (see the Software section). Its main advantage is a novel technique for optimizing conjunctive queries in a massively parallel setting, using n-ary join operators; this allow the optimization algorithm to build plans which are as flat as possible. These results apply beyond the RDF conjunctive query evaluation to the general setting of relational conjunctive query processing in a massively parallel context.

Another crucial result of the year is the publication of the PAXQuery framework for massively processing XML queries based on the Stratosphere (now Apache Flink) platform [3] . We show that our algebra-based approach allows to capture the expressive processing performed by an XQuery query and to compile it efficiently into massively distributed plans which are then evaluated by the Flink platform; this outperforms a set of state-of-the-art approaches for evaluating XQuery queries in a parallel environment. The system was also demonstrated at SIGMOD [11] .