Department of Database and Information Systems, Institute of Computer Science, University of Innsbruck, Innsbruck, Austria. sebastian.schoenherr@uibk.ac.at|Department of Database and Information Systems, Institute of Computer Science, University of Innsbruck, Innsbruck, Austria. sebastian.schoenherr@uibk.ac.at|Department of Database and Information Systems, Institute of Computer Science, University of Innsbruck, Innsbruck, Austria. sebastian.schoenherr@uibk.ac.at|Department of Database and Information Systems, Institute of Computer Science, University of Innsbruck, Innsbruck, Austria. sebastian.schoenherr@uibk.ac.at|Department of Database and Information Systems, Institute of Computer Science, University of Innsbruck, Innsbruck, Austria. sebastian.schoenherr@uibk.ac.at|Department of Database and Information Systems, Institute of Computer Science, University of Innsbruck, Innsbruck, Austria. sebastian.schoenherr@uibk.ac.at