Reverse k Nearest Neighbor Search over Trajectories

GPS enables mobile devices to continuously provide new opportunities to improve our daily lives. For example, the data collected in applications created by Uber or Public Transport Authorities can be used to plan transportation routes, estimate capacities, and proactively identify low coverage areas. In this paper, we study a new kind of query-Reverse k Nearest Neighbor Search over Trajectories (RkNNT), which can be used for route planning and capacity estimation. Given a set of existing routes DR, a set of passenger transitions DT, and a query route Q, a RkNNT query returns all transitions that take Q as one of its k nearest travel routes. To solve the problem, we first develop an index to handle dynamic trajectory updates, so that the most up-to-date transition data are available for answering a RkNNT query. Then we introduce a filter refinement framework for processing RkNNT queries using the proposed indexes. Next, we show how to use RkNNT to solve the optimal route planning problem MaxRkNNT (MinRkNNT), which is to search for the optimal route from a start location to an end location that could attract the maximum (or minimum) number of passengers based on a pre-defined travel distance threshold. Experiments on real datasets demonstrate the efficiency and scalability of our approaches. To the best of our best knowledge, this is the first work to study the RkNNT problem for route planning.Comment: 12 page

An incremental database access method for autonomous interoperable databases

We investigated a number of design and performance issues of interoperable database management systems (DBMS's). The major results of our investigation were obtained in the areas of client-server database architectures for heterogeneous DBMS's, incremental computation models, buffer management techniques, and query optimization. We finished a prototype of an advanced client-server workstation-based DBMS which allows access to multiple heterogeneous commercial DBMS's. Experiments and simulations were then run to compare its performance with the standard client-server architectures. The focus of this research was on adaptive optimization methods of heterogeneous database systems. Adaptive buffer management accounts for the random and object-oriented access methods for which no known characterization of the access patterns exists. Adaptive query optimization means that value distributions and selectives, which play the most significant role in query plan evaluation, are continuously refined to reflect the actual values as opposed to static ones that are computed off-line. Query feedback is a concept that was first introduced to the literature by our group. We employed query feedback for both adaptive buffer management and for computing value distributions and selectivities. For adaptive buffer management, we use the page faults of prior executions to achieve more 'informed' management decisions. For the estimation of the distributions of the selectivities, we use curve-fitting techniques, such as least squares and splines, for regressing on these values

Dagstuhl Seminar - Integrating Spatial and Temporal Databases

Spatial databases incorporate the notion of space in order to accommodate the requirements for databases that allow reasoning about 2D and 3D such as geographical applications( GIS). Their study exists for more than twenty years. Lately, is triggered even more by the progress achieved in the power of computers which permits them to accommodate graphics and easily perform geometrical calculations. Spatial databases form an autonomous, active research community and a series of International Conferences are regularly organised (series of Symposium on Spatial Databases and Symposium on Spatial Data Handling). A number of Journals concern with spatial Databases as well(Cartographica, International Journal of Geographic Information Systems). The National Center for Geographic Information and Analysis (NCGIA, USA) is an established body coordinating research in Spatial Databases and their beneficial application in geography. OpenGIS is an International Consortium trying to bring Interoperability into Geographic Information Systems.Temporal databases incorporate the concept of time to create high-level abstractions useful in database applications. This has been an active area of research for about twenty years. In the last few years the importance of the temporal database area has been recognised by the international scientific community. This recognition came in part in the form of the ARPA/NSF sponsored International Workshop on Temporal Database Infrastructure in 1993, a VLDB-affiliated temporal workshop in 1995, a special section of the IEEE Transactions on Knowledge and Data Engineering on temporal and real time databases published in August 1995, and the incorporation of temporal constructs, proposed by the temporal database community, in the soon-to-be standardised SQL3 language.The main objective of the seminar was to bring together researchers from the two areas that have been working independently from each other and only recently have started to talk to each other. For example, research work on integration has started appearing on the main conferences and publications of each discipline.One of the main issues discussed was whether it is feasible and if yes, how the research should be further integrated and if possible, what the mechanisms that the community can define so as to accelerate the process of developing a spatiotemporal infrastructure.The “Integrating Spatial and Temporal Databases” seminar focused on establishing the foundations of a new discipline and also the future directions of that discipline, with respect to both research issues and the means to incorporate spatiotemporal databases into main-stream application development. A list of topics discussed at this seminar follows:• Strategic discussions about the future of spatiotemporal databases as a discipline. Evaluation of the current state of the art with respect to the current trends in the DBMS tools and standards.• Research Issues in Spatial and Temporal Databases: What is important? • Spatiotemporal data models: relational, object-oriented, deductive and hybrid models. Where do the spatial and temporal capabilities fit in? • Spatiotemporal user interfaces and languages. Update and retrieval languages for various types of temporal data models. • Implementation issues in spatiotemporal databases. Issues that arise from experience of implementors and users and the agenda for research into these areas and transition to use in practice. • Issue a "call for action" to the community (academia and vendors alike) This seminar brought together over sixty researchers from fifteen countries that have dealt with different disciplines (spatial and temporal), as well as developers of databases and users, to conduct a fruitful discussion and evaluation of the activities thus far with a view on establishing the foundations of a new discipline that of spatiotemporal databases. There was a general agreement that there is still work to be done in Spatiotemporal Design, Data Models, Query Languages and Indexing while areas such as Temporal Data Models and Algebras are almost complete. Spatiotemporal Data Mining, Query Processing and Optimisation will produce significant results in the next ten years

Dagstuhl Seminar - Integrating Spatial and Temporal Databases

Spatial databases incorporate the notion of space in order to accommodate the requirements for databases that allow reasoning about 2D and 3D such as geographical applications( GIS). Their study exists for more than twenty years. Lately, is triggered even more by the progress achieved in the power of computers which permits them to accommodate graphics and easily perform geometrical calculations. Spatial databases form an autonomous, active research community and a series of International Conferences are regularly organised (series of Symposium on Spatial Databases and Symposium on Spatial Data Handling). A number of Journals concern with spatial Databases as well(Cartographica, International Journal of Geographic Information Systems). The National Center for Geographic Information and Analysis (NCGIA, USA) is an established body coordinating research in Spatial Databases and their beneficial application in geography. OpenGIS is an International Consortium trying to bring Interoperability into Geographic Information Systems.Temporal databases incorporate the concept of time to create high-level abstractions useful in database applications. This has been an active area of research for about twenty years. In the last few years the importance of the temporal database area has been recognised by the international scientific community. This recognition came in part in the form of the ARPA/NSF sponsored International Workshop on Temporal Database Infrastructure in 1993, a VLDB-affiliated temporal workshop in 1995, a special section of the IEEE Transactions on Knowledge and Data Engineering on temporal and real time databases published in August 1995, and the incorporation of temporal constructs, proposed by the temporal database community, in the soon-to-be standardised SQL3 language.The main objective of the seminar was to bring together researchers from the two areas that have been working independently from each other and only recently have started to talk to each other. For example, research work on integration has started appearing on the main conferences and publications of each discipline.One of the main issues discussed was whether it is feasible and if yes, how the research should be further integrated and if possible, what the mechanisms that the community can define so as to accelerate the process of developing a spatiotemporal infrastructure.The “Integrating Spatial and Temporal Databases” seminar focused on establishing the foundations of a new discipline and also the future directions of that discipline, with respect to both research issues and the means to incorporate spatiotemporal databases into main-stream application development. A list of topics discussed at this seminar follows:• Strategic discussions about the future of spatiotemporal databases as a discipline. Evaluation of the current state of the art with respect to the current trends in the DBMS tools and standards.• Research Issues in Spatial and Temporal Databases: What is important? • Spatiotemporal data models: relational, object-oriented, deductive and hybrid models. Where do the spatial and temporal capabilities fit in? • Spatiotemporal user interfaces and languages. Update and retrieval languages for various types of temporal data models. • Implementation issues in spatiotemporal databases. Issues that arise from experience of implementors and users and the agenda for research into these areas and transition to use in practice. • Issue a "call for action" to the community (academia and vendors alike) This seminar brought together over sixty researchers from fifteen countries that have dealt with different disciplines (spatial and temporal), as well as developers of databases and users, to conduct a fruitful discussion and evaluation of the activities thus far with a view on establishing the foundations of a new discipline that of spatiotemporal databases. There was a general agreement that there is still work to be done in Spatiotemporal Design, Data Models, Query Languages and Indexing while areas such as Temporal Data Models and Algebras are almost complete. Spatiotemporal Data Mining, Query Processing and Optimisation will produce significant results in the next ten years

VIEWCACHE: An incremental pointer-base access method for distributed databases. Part 1: The universal index system design document. Part 2: The universal index system low-level design document. Part 3: User's guide. Part 4: Reference manual. Part 5: UIMS test suite

The goal of the Universal Index System (UIS), is to provide an easy-to-use and reliable interface to many different kinds of database systems. The impetus for this system was to simplify database index management for users, thus encouraging the use of indexes. As the idea grew into an actual system design, the concept of increasing database performance by facilitating the use of time-saving techniques at the user level became a theme for the project. This Final Report describes the Design, the Implementation of UIS, and its Language Interfaces. It also includes the User's Guide and the Reference Manual