@phdthesis{Wiesner2004, author = {Wiesner, Christian}, title = {Query Evaluation Techniques for Data Integration Systems}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus-406}, school = {Universit{\"a}t Passau}, year = {2004}, abstract = {In this work we present novel query evaluation techniques for data integration systems in different environments, ranging from a central data-warehouse approach, over distributed virtual market places, to peer-to-peer (P2P) systems. Based on a new distributed evaluation technique, the so-called HyperQueries, we present a reference architecture for distributed virtual market places. These HyperQueries enable us to dynamically construct query evaluation plans by referencing sub-plans in the Internet. Furthermore, the process of data integration is structured. Subsequently, we investigate P2P data integration systems without central instances. We introduce so-called Super-Peers which structure a P2P network. Using this Super-Peer based network we "unroll" queries. This allows us to execute even user-defined operators nearby the data sources. Finally, we propose novel, efficient join algorithms for decision support queries in central data-warehouse systems. The proposed order-preserving hashjoins and generalized hashteams are based on early sorting and early partitioning of the inputs and can speed up the query evaluation up to orders of magnitutes.}, subject = {Abfrageverarbeitung}, language = {en} } @phdthesis{Braumandl2002, author = {Braumandl, Reinhard}, title = {Quality of Service and Optimization in Data Integration Systems}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:739-opus-279}, school = {Universit{\"a}t Passau}, year = {2002}, abstract = {This work presents techniques for the construction of a global data integrations system. Similar to distributed databases this system allows declarative queries in order to express user-specific information needs. Scalability towards global data integration systems and openness were major design goals for the architecture and techniques developed in this work. It is shown how service composition, extensibility and quality of service can be supported in an open system of providers for data, functionality for query processing operations, and computing power.}, subject = {Dienstg{\"u}te}, language = {en} }