62611509
Query optimization in distributed databases through load balancing
Abstract : As technology advances, computing environments composed of large numbers of workstations and mainframes connected by a high bandwidth local area network become attractive. These systems typically support a large number of application classes, and the heterogeneity of their workload, coupled with the decentralization of the systems, can lead to load imbalances across the network. This work attempts to study the benefits of load balancing strategies in the context of a particular application, distributed database systems. It was felt that, by focusing on a specific area, the problem would become more tractable. The choice of database management systems can be justified not only by their intrinsic importance, but also by the adaptability of load balancing strategies to query optimization algorithms. In order to determine whether load balancing strategies can indeed be adapted to current optimizers with a moderate amount of effort and to see whether the resulting performance benefits are sizable, both benchmarking and simulation experiments were carried out.
206634710
Altruistic Locking: A Strategy for Coping with Long Lived Transactions
41657422
Long-Term Caching Strategies for Very Large Distributed File Systems
5881433
An advisor for flexible working sets
The traditional model of virtual memory working sets does not account for programs that can adjust their working sets on demand. Examples of such programs are garbage-collected systems and databases with block cache buffers. We present a memory-use model of such systems, and propose a method that may be used by virtual memory managers to advise programs on how to adjust their working sets. Our method tries to minimize memory contention and ensure better overall system response time. We have implemented a memory “advice server” that runs as a non-privileged process under Berkeley Unix. User processes may ask this server for advice about working set sizes, so as to take maximum advantage of memory resources. Our implementation is quite simple, and has negligible overhead, and experimental results show that it results in sizable performance improvements.
59895916
Concurrency Control and Recovery for Global Procedures in Federated Database Systems
16077675
Hybrid Multi-agent Systems: Integrating Swarming and BDI Agents
The individual agents that interact in a multi-agent system typically exist along a continuum ranging from heavyweight cognitive agents (often of the "BDI" type) to lightweight agents with limited individual processing (digital ants). Most systems use agents from a single position along this spectrum. We have successfully implemented several systems in which agents of very different degrees of internal sophistication interact with one another. Based on this experience, we identify several different ways in which agents of different kinds can be integrated in a single system, and offer observations and lessons from our experiences.
29591299
Trade Press News
42014672
Trade Press News - Announcement and Preface