Big RDF datasets need to be stored and processed in distributed RDF data stores that are built on top of cluster servers. Several partitioning schemes like horizontal, vertical, and hash partitioning, exist that allow for splitting the datasets into several nodes, in order to achieve scalability and efficient query processing. The goal of this thesis is to study graph partitioning approaches for RDF data, compare the state of the art, and implement corresponding algorithms that will be integrated into the SANSA framework.
RDF compression techniques (en-US)
As a starting point, realizing a fresh state-of-the-art of compression techniques for RDF could be made. These techniques can mainly be divided into two families: the ones that compress as much as possible datasets in order to make transfers easier (see e.g. the study of Fernández et al.) and the ones which still allow data to be queried (see e.g. the HDT structure). Secondly, a reflexion on a new compression model may be thought about and then realized/implemented successfully -obviously, a already have some suggestion which could help the student 😉 like for instance try to compress the RDF graphs according to patterns which could be used in parallel of SPARQL query shapes.
Data quality is considered as a multidimensional concept that covers different aspects of quality such as accuracy, completeness, and timeliness. With the advent of Big Data, traditional quality assessment techniques are facing different challenges. Therefore, we should adopt the traditional techniques to big data technologies. The goal of this thesis is to re-implement the assessment techniques in the SANSA framework.
Recommendation system for RDF partitioners (en-US)
In order to store and query big RDF datasets efficiently in distributed environments, different partitioning techniques need to be implemented. Several techniques have been proposed for splitting Big RDF Data, ranging from vertical, hash, graph to semantic-based partitioners. However, the selection of the “best partitioner” depends highly on the structure of the dataset and the query efficiency and effectiveness are coupled to the query engine used. The goal of this thesis will be to develop a recommender system that will suggest the “best partitioner” based on the structure of the data and specific requirements.