Database Workload Management (Dagstuhl Seminar 12282)

This report documents the program and the outcomes of Dagstuhl Seminar 12282 "Database Workload Management". Dagstuhl Seminar 12282 was designed to provide a venue where researchers can engage in dialogue with industrial participants for an in-depth exploration of challenging industrial workloads, where industrial participants can challenge researchers to apply the lessons-learned from their large-scale experiments to multiple real systems, and that would facilitate the release of real workloads that can be used to drive future research, and concrete measures to evaluate and compare workload management techniques in the context of these workloads

10381 Summary and Abstracts Collection -- Robust Query Processing

Dagstuhl seminar 10381 on robust query processing (held 19.09.10 - 24.09.10) brought together a diverse set of researchers and practitioners with a broad range of expertise for the purpose of fostering discussion and collaboration regarding causes, opportunities, and solutions for achieving robust query processing. The seminar strove to build a unified view across the loosely-coupled system components responsible for the various stages of database query processing. Participants were chosen for their experience with database query processing and, where possible, their prior work in academic research or in product development towards robustness in database query processing. In order to pave the way to motivate, measure, and protect future advances in robust query processing, seminar 10381 focused on developing tests for measuring the robustness of query processing. In these proceedings, we first review the seminar topics, goals, and results, then present abstracts or notes of some of the seminar break-out sessions. We also include, as an appendix, the robust query processing reading list that was collected and distributed to participants before the seminar began, as well as summaries of a few of those papers that were contributed by some participants

View materialization issues in object-oriented databases.

Recent advances in information technology introduced a need for techniques to integrate heterogeneous sources, to cache and re-use results of queries across multiple information sources (data warehousing), to support customized interfaces to shared data, and to integrate such mechanisms with the powerful constructs of the object-oriented programming model. Object-oriented database (OODB) view technology can help provide such techniques. A view is a query that is stored and given a name by which it can be used in other queries. Typically a view's contents are derived using the view's stored query. View materialization, i.e., the generation of derived extents of views, improves the performance of queries by eliminating the need for such recomputation. However, it requires the maintenance of the contents of materialized views in the face of updates. This thesis proposes a methodology for the support and maintenance of materialized OODB views. We have implemented a prototype of this methodology in the context of the MultiView OODB view system, one of the first view management systems for object-oriented databases and (to the best of our knowledge) the first to support updatable incrementally materialized object-oriented views. The primary contribution of this work is the development of algorithms that exploit OO characteristics for the incremental maintenance of materialized OODB views. In particular, we address two potential inefficiencies to which update propagation algorithms are subject--the propagation of updates to irrelevant derived classes and the propagation of self-cancelling updates. We present cost models and experimental results that demonstrate that our techniques of hierarchical registration of the dependency of virtual classes on properties invoked in their predicates and derivation-ordered propagation successfully address these problems. We also propose a new Satisfiability Indicating Multi-Index (SMX) organization specifically tailored to optimize the maintenance of views defined by selection queries along aggregation paths (path query views). A key characteristic of our SMX solution is to maintain minimal partial information indicating whether or not the endpoints reachable from an object satisfies the query predicate. Our cost models confirm that the SMX dramatically improves upon the performance of traditional index structures with respect to the problem of path query view maintenance.Ph.D.Computer Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/105107/1/9635546.pdfDescription of 9635546.pdf : Restricted to UM users only

Robust Query Processing (Dagstuhl Seminar 12321)

The 2012 Dagstuhl 12321 Workshop on Robust Query Processing, held from 5--10 August 2012, brought together researchers from both academia and industry to discuss various aspects of robustness in database management systems and ideas for future research. The Workshop was designed as a sequel to an earlier Workshop, Dagstuhl Workshop 10381, that studied a similar set of topics. In this article we summarize some of the main discussion topics of the 12321 Workshop, the results to date, and some open problems that remain