850911
Usability-based caching of query results in OLAP systems
In this paper we propose a new cache management scheme for online analytical processing (OLAP) systems based on the usability of query results in rewriting and processing other queries. For effective admission and replacement of OLAP query results, we consider the benefit of query results not only for recently issued queries but for the expected future queries of a current query. We exploit semantic relationships between successive queries in an OLAP session, which are derived from the interactive and navigational nature of OLAP query workloads, in order to classify and predict subsequent future queries. We present a method for estimating the usability of query results for the representative future queries using a probability model for them. Experimental evaluation shows that our caching scheme using the past and future usability of query results can reduce the cost of processing OLAP query workloads effectively only with a small cache size and outperforms the previous caching strategies for OLAP systems.
17546848
Analysis of Fuzzy Operators for High Quality Information Retrieval
Kim, M.H., J.H. Lee and Y.J. Lee, Analysis of fuzzy operators for high quality information retrieval. Information Processing Letters 46 (1993) 251-256. It has been argued that the conventional fuzzy set model based on the MIN and MAX operators is not appropriate for a model of information retrieval systems due to the properties of the MIN and MAX operators adverse to retrieval effectiveness. In this paper we investigate the behavioral aspects of various fuzzy operators and address the properties which are important in achieving high quality document rankings. We then present the fuzzy set model based on positively compensatory operators, which provides higher retrieval effectiveness than the conventional fuzzy set model. It is also described that the behavior of the proposed fuzzy set model almost coincides with that of the extended boolean model.
8831551
A per-object based hybrid concurrency control
Existing concurrency control algorithms do not conform well to various environments in the performance perspective. Each algorithm has some assumption on the conflict characteristic of its execution environment, and its performance degrades when the assumption fails. A per-object hybrid scheme integrating a two phase locking algorithm with a parallel validation technique is presented to solve this problem. Read and write accesses on each database object are controlled by one algorithm at a time. This controlling algorithm can alter while transactions are running, in order to enhance the overall system performance. In the simulation study, the proposed scheme with the proposed algorithm alteration strategy is shown to conform well to various execution environments, better than both the two phase locking algorithm and the parallel validation technique.
38239153
Qualitative Behavior Modeling of Information Processing Components
This paper presents qualitative behavior modeling of Information Processing Components(IPCs), which are domain-specific software components for modeling reusable functions in database management systems(DBMSs). After introducing a detailed formal syntax of IPCs, we propose their modular, qualitative behavior generation mechanism. The proposed mechanism is based on qualitative modeling and simulation, thus produces a sequence of temporal state transitions of modeled IPCs. The proposed modeling mechanism aims to facilitate the scientific measurement of
26557344
A Knowledge-Based Approach to Rank Documents for Boolean Queries
10552627
An efficient parallel join algorithm based on hypercube-partitioning
Many parallel join algorithms have been proposed so far but most of which are developed focused on minimizing the disk I/O and CPU costs. The communication cost, however, is also an important factor that can significantly affect the join processing performance in multiprocessor systems. We propose an efficient parallel join algorithm, called Cube-Robust, for hypercube multicomputers. The proposed algorithm is developed based on the observation that the size ratio of two relations to be joined is the dominant factor in the communication cost. We develop the analytic cost model for the proposed join algorithm. The performance comparisons show that the Cube-Robust join algorithm works better than others proposed earlier in a wide range of size ratios.<<ETX>>
26676459
Progressive Transaction Recovery in Distributed DB/DC Systems
The demand for on-line transaction processing has grown rapidly in recent years. To meet the transaction demand, several DB (database management) and DC (data communication management) subsystems can be coupled together to form a distributed DB/DC system. A key problem is to provide these distributed systems with effective means to recover transactions upon failure while paying little performance penalty during normal processing. Also, there should be minimal interference of fault-free components, during the recovery of failed component. By decentralizing recovery management, and using transaction level structural information to eliminate costly lower level handshaking protocols, proposed progressive transaction recovery protocols seek to solve the problem. A queueing model for evaluating the transaction response time during normal processing for the progressive and pessimistic protocols is developed and solved, via simulation. The progressive recovery protocols are shown to reduce normal processing overhead and lead to performance improvement over the pessimistic protocol.
30123293
Key Management in Wireless Sensor Networks
Wireless sensor networks hold the promise of facilitating large-scale, real-time data processing in complex environments. As sensor networks edge closer towards widespread deployment, security issues become a central concern. Key management in wireless sensor networks is a challenging problem. Computationally complex asymmetric crypto techniques are unsuitable for use in resource-constrained sensor nodes and use of symmetric cryptography makes the entire network vulnerable in the event of node compromise. This paper presents a key management scheme that satisfies both operational and security requirements of distributed wireless sensor networks. The proposed scheme accommodates other techniques like data aggregation for energy efficiency and watchdog mechanism for intrusion monitoring. Also, the proposed scheme is generic enough so that it can be applied to variety of sensor network protocols.
9352277
An ATM Switch Capacity Allocation Problem
In this paper, we consider a capacity allocation problem arising in the context of deploying asynchronous transfer mode (ATM) networks. Given types of ATM switches, the problem is to find an optimal allocation of capacity such that the total cost of installed switch modules is minimized, while satisfying all traffic demands. We formulate the problem as an integer programming model, which can be conceptualized as a generalized bin packing problem with capacity constraints. We then develop a surrogate constraint technique of the formulation for enhancing the representation of the model. Guided by the tight lower bound of the surrogate relaxation, we devise an effective tabu search heuristic that provides good quality solutions with guaranteed optimality. We present promising computational results that show the viability of the proposed heuristic and lower bounding methods, and that provide insights into implementation for configuring ATM switch in practice.
10094158
System and software designs for transaction processing in asymmetric communication environments
Observing that it is impractical to use traditional methods to control concurrency in broadcast-based asymmetric communication environments, we introduce a concurrency control protocol designed for broadcast-based transaction processing called Server Timestamp and Update Broadcast Supported Concurrency (STUBcast). STUBcast supports two new correctness criteria proposed in this paper—Single Serializability and Local Serializability. These criteria are weaker than global serializability, but are practical and easier to achieve in broadcast environments. This article also discusses the software design for the simulation program and the protocol implementation. Simulation results collected using our simulation program suggest that STUBcast could be very efficient in realistic application environments. Copyright © 2003 John Wiley & Sons, Ltd.
509415
A New Class of Non-stationary Interpolatory Subdivision Schemes Based on Exponential Polynomials
We present a new class of non-stationary, interpolatory subdivision schemes that can exactly reconstruct parametric surfaces including exponential polynomials. The subdivision rules in our scheme are interpolatory and are obtained using the property of reproducing exponential polynomials which constitute a shift-invariant space. It enables our scheme to exactly reproduce rotational features in surfaces which have trigonometric polynomials in their parametric equations. And the mask of our scheme converges to that of the polynomial-based scheme, so that the analytical smoothness of our scheme can be inferred from the smoothness of the polynomial based scheme.