Ontology-based data access (OBDA) has gained attention in recent years for providing access to large volumes of data by using ontologies as a conceptual layer and exploring their ability to describe domains and deal with data incompleteness. This is done through mappings that connect the data in the database to the vocabulary of the ontology. The first OBDA studies were about data stored in rel...

Within the Big Data trend, there is an increasing interest in Not-only-SQL systems (NoSQL). These systems are promising candidates for implementing data warehouses particularly due to the data structuration/storage possibilities they offer. In this paper, we investigate data warehouse instantiation using a document-oriented system (a special class of NoSQL systems). On the one hand, we analyze ...

The proliferation in Web 2.0 applications has increased the volume, velocity, and variety of data sources which have exceeded the limitations and expected use cases of traditional relational DBMSs. Cloud serving NoSQL data stores address these concerns and provide replication mechanisms to ensure fault tolerance, high availability, and improved scalability. In this paper, we empirically explore...

Property preserving encryption (PPE) can enable database systems to process queries over encrypted data. While a lot of research in this area focusses on doing so with SQL databases, NoSQL (Not only SQL) cloud databases are good candidates either. On the one hand, they usually provide enough space to store the typically larger ciphertexts and special indexes of PPE-schemes. On the other hand in...

In this incessant science and technological era, where advances in web technology and the production of mobile devices and sensors connected to the Internet are resulting to voluminous amount of structured, semi-structured and unstructured data, called Big Data, the demand for technologies with extensive processing and storage requirements is rising to persuasively process such data i.e. Big Da...

Schemafreie NoSQL-Datenbanken wie MongoDB bieten in der Softwareentwicklung groûe Flexibilität. Dies ist vor allem in der agilen Softwareentwicklung sehr nützlich, bei der die Software früh veröffentlicht und in kurzen Abständen aktualisiert wird. Des Weiteren werden in der professionellen Anwendungsentwicklung gerne Objektmapper als Bindestück zwischen einer objektorientierten Sprache und dem ...

Relational database systems are still the first choice for the realization of business application systems. They are used as operational databases to persist business process data or as the basis for data warehouse systems. In recent years, the NoSQL-movement proposed a number of new non-relational data stores because of changing requirements of Web 2.0 applications and related limitations of r...