Allocation of rules to sites in a distributed deductive database system is an important and challenging task especially for a large knowledge base. We identify communication cost in rule execution to be the primary ba...
详细信息
Allocation of rules to sites in a distributed deductive database system is an important and challenging task especially for a large knowledge base. We identify communication cost in rule execution to be the primary basis for decomposing a global knowledge base into clusters for their allocation to sites. We show that the problem of optimal allocation is a 0-1 quadratic programming problem, which has prohibitive execution times for large knowledge bases. We propose an efficient heuristic algorithm for rule allocation and study its performance experimentally. We represent a knowledge base as a hierarchy and characterize it in terms of height and inherent clusters with overlaps. The experimental results of the heuristic algorithm on random hierarchies as well as on hierarchies with varying heights and overlaps are seen to be close to the optimal solution.
The paper describes recent progress in research on database system support for executing multimedia presentations. It proposes the general concept of Reactive Playout Management to adjust multimedia presentations. Thi...
详细信息
ISBN:
(纸本)0818674695
The paper describes recent progress in research on database system support for executing multimedia presentations. It proposes the general concept of Reactive Playout Management to adjust multimedia presentations. This adjustment can be required due to performance fluctuations as in the absence of end-to-end quality of service guarantees, cost constraints specified by the user, and other reasons. A concrete concept to realize Performance-Based Reactive Playout Management in distributed Multimedia databasesystems is proposed. This covers the identification of respective components in distributeddatabase system architectures along with corresponding algorithms.
A distributeddatabase management system (DDBMS) offers an organization the ability to centralize or decentralize its management of data. In this paper we examine how the likelihood of DDBMS adoption is affected by fo...
详细信息
ISBN:
(纸本)0897915720
A distributeddatabase management system (DDBMS) offers an organization the ability to centralize or decentralize its management of data. In this paper we examine how the likelihood of DDBMS adoption is affected by four organizational factors, drawn from previous research and a pilot study conducted by the authors: (1) centralization - decentralization of management decision making;(2) centralization - decentralization of the information systems function;(3) attitudes of top management toward technology;and (4) forces behind information technology selection.
As business corporations continue to expand, there is growing importance of distributed computing and distributeddatabases. distributeddatabases are generally heterogeneous, large, and complex. A likely scenario is ...
详细信息
ISBN:
(纸本)0780337166
As business corporations continue to expand, there is growing importance of distributed computing and distributeddatabases. distributeddatabases are generally heterogeneous, large, and complex. A likely scenario is an eventual existence of a variety of heterogeneous inter-operating databases distributed over a network, which gives rise to the interoperability problem. This paper proposes the use of artificial intelligence techniques to address the problem of interoperability.
A novel database system service called playout management service which performs multimedia presentations was proposed recently. In distributed multimedia databasesystems without end-to-end guarantees, such a playout...
详细信息
ISBN:
(纸本)0818672404
A novel database system service called playout management service which performs multimedia presentations was proposed recently. In distributed multimedia databasesystems without end-to-end guarantees, such a playout management service faces the potential problem that system performance can become insufficient when realizing a stored presentation. This problem can be overcome by making the playout management service reactive such that it balances the data amount to be fetched from a remote multimedia database with the system performance available. For the users this means that, a running presentation is adapted by the playout management service. In this paper, we propose the concept of δ-set to adapt the execution of arbitrary multimedia presentations in an optimized way. We show a heuristic scheme to identify the most adequate δ-set with respect to (1) the actual system state, (2) the user preferences, and (3) the specific properties of multimedia presentations.
distributeddatabases offer a complete range of desirable features: availability, reliability, and responsiveness. However, all of these benefits are at the expense of some extra management;main issues considered in l...
详细信息
ISBN:
(纸本)9729881618
distributeddatabases offer a complete range of desirable features: availability, reliability, and responsiveness. However, all of these benefits are at the expense of some extra management;main issues considered in literature as the base of a tuned distributeddatabase system could be data replication and synchronization, concurrency access, distributed query optimization or performance improvement. Work presented here tries to provide some clues to the last point considering an issue which has not been taken enough into account under our humble opinion: load balancing of these distributedsystems. It is tried to be shown how the right load balancing policy influences the performance of a distributeddatabase management system, and more concretely a shared-nothing one.
In this paper, we propose a new approach for parallel query processing in distributed object databasesystems. An object query is disassembled into a set of query packets which can be processed independently and in pa...
详细信息
In this paper, we propose a new approach for parallel query processing in distributed object databasesystems. An object query is disassembled into a set of query packets which can be processed independently and in parallel at each site. Three alternative query packet processing strategies are discussed. Comparing with the conventional OID-join approach, the query packet approach dramatically reduces the response time and gives better work load balancing.
The estimated sizes of temporary files are one of the most important statistics used by an Optimizer in generating a minimum cost processing strategy. Statistical information is the primary input to the estimation tec...
详细信息
Up to now in the field of temporal databasesystems there have been investigated 3 kinds of time: valid time, transaction time and indeterminate valid time. Indeterminate valid time serves to describe the timestamps a...
详细信息
As database technology advances rapidly, there are usually heterogeneous databases used by different departments in an enterprise. On the other hand, the object-oriented technology is becoming the dominant application...
详细信息
As database technology advances rapidly, there are usually heterogeneous databases used by different departments in an enterprise. On the other hand, the object-oriented technology is becoming the dominant application development paradigm. Thus, there is a data modeling gap between applications and heterogeneous databases. In this paper we present some main architecture aspects of the system VH-DBS, which has been developed by an ongoing research project. This architecture provides a way to support cooperative access to distributed heterogeneous databases and to fill the data modeling gap in a distributed heterogeneous environment. Our work contributes not only to an implementation solution but also to an architectural framework and paradigmatic solution.
暂无评论