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Numerical Analysis and Scientific Computing Commons™

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Singapore Management University

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Articles 1051 - 1060 of 1060

Full-Text Articles in Numerical Analysis and Scientific Computing

Multiclass Query Scheduling In Real-Time Database Systems, Hwee Hwa Pang, Michael J. Carey, Miron Livny Aug 1995

Multiclass Query Scheduling In Real-Time Database Systems, Hwee Hwa Pang, Michael J. Carey, Miron Livny

Research Collection School Of Computing and Information Systems

In recent years, a demand for real-time systems that can manipulate large amounts of shared data has led to the emergence of real-time database systems (RTDBS) as a research area. This paper focuses on the problem of scheduling queries in RTDBSs. We introduce and evaluate a new algorithm called Priority Adaptation Query Resource Scheduling (PAQRS) for handling both single class and multiclass query workloads. The performance objective of the algorithm is to minimize the number of missed deadlines, while at the same time ensuring that any deadline misses are scattered across the different classes according to an administratively-defined miss distribution. …

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Multiple Query Optimization With Depth-First Branch-And-Bound And Dynamic Query Ordering, Ee Peng Lim, Ahmet Cosar, Jaideep Srivastava Jan 1995

Multiple Query Optimization With Depth-First Branch-And-Bound And Dynamic Query Ordering, Ee Peng Lim, Ahmet Cosar, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

In certain database applications such as deductive databases, batch query processing, and recursive query processing etc., usually a single query gets transformed into a set of closely related database queries. Also, great benefits can be obtained by executing a group of related queries all together in a single unified multi-plan instead of executing each query separately. In order to achieve this Multiple Query Optimization (MQO) identifies common task(s) (e.g. common subexpressions, joins, etc.) among a set of query plans and creates a single unified plan (multi-plan) which can be executed to obtain the required outputs for all queries at once. …

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A Load Distribution Through Competition For Workstation Clusters, Kam Hong Shum, Muslim Bozyigit Nov 1994

A Load Distribution Through Competition For Workstation Clusters, Kam Hong Shum, Muslim Bozyigit

Research Collection School Of Computing and Information Systems

The aim of this work is to develop a competition driven solution approach for load distribution in distributed computing system (DCS) environments. The subject DCS is composed of a set of workstation clusters. The study deals with concurrent applications, but assumes the existence of the independent tasks executing on individual workstations as well. Akin to conventional load balancing algorithms, the approach considers two phases; the partitioning phase and the mapping phase. Each phase is based on the application and the DCS data which is translated into market data, mainly price. The price is governed by the demand and supply of …

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Automating Output Size And Reuse Metrics In A Repository-Based Computer-Aided Software Engineering (Case) Environment, R. D. Banker, Robert J. Kauffman, C. Wright, D. Zweig Mar 1994

Automating Output Size And Reuse Metrics In A Repository-Based Computer-Aided Software Engineering (Case) Environment, R. D. Banker, Robert J. Kauffman, C. Wright, D. Zweig

Research Collection School Of Computing and Information Systems

Measurement of software development productivity is needed in order to control software costs, but it is discouragingly labor-intensive and expensive. Computer-aided software engineering (CASE) technologies-especially repository-based, integrated CASE-have the potential to support the automation of this measurement. We discuss the conceptual basis for the development of automated analyzers for function point and software reuse measurement for object-based CASE. Both analyzers take advantage of the existence of a representation of the application system that is stored within an object repository, and that contains the necessary information about the application system. We also discuss metrics for software reuse measurement, including reuse leverage, …

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Asynchronous Transaction Commitment In Federated Database Systems, San-Yih Hwang, Ee Peng Lim, Jaideep Srivastava Dec 1993

Asynchronous Transaction Commitment In Federated Database Systems, San-Yih Hwang, Ee Peng Lim, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

We propose a new (and restricted) model for global transactions which allows asynchronous commitment of subtransactions. Our model requires each global transaction to have a fixed structure with update to the data in at most one database. Based on this transaction model, we present two concurrency control algorithms, namely Asynchronous Site Graph and Asynchronous VirtGlobalSG, which employ asynchronous commitment and achieve global serializability. Compared to other proposed algorithms, our algorithms employ asynchronous commitment so as to increase transaction performance. Furthermore, our algorithms do not put restrictions on transaction data access or local histories.

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Query Optimization And Processing In Federated Database Systems, Ee Peng Lim, Jaideep Srivastava Nov 1993

Query Optimization And Processing In Federated Database Systems, Ee Peng Lim, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

No abstract provided.

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Multiple Query Optimization With Depth-First Branch-And-Bound, Ahmet Cosar, Ee Peng Lim, Jaideep Srivastava Nov 1993

Multiple Query Optimization With Depth-First Branch-And-Bound, Ahmet Cosar, Ee Peng Lim, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

In certain database applications such as deductive databases, batch query processing, and recursive query processing etc., a single query can be transformed into a set ofclosely related database queries. Great benefits can be obtained by executing a group of related queries all together in a single unijied multi-plan instead of executing each query separately. In order to achieve this, Multiple Query Optimization (MQO) identifies common task(s) (e.g. common subezpressions, joins, etc.) among a set of query plans and creates a single unified plan (multiplan) which can be executed to obtain the required outputs forall queries at once. In this paper, …

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Entity Identification In Database Integration: An Evidential Reasoning Approach, Ee Peng Lim, Jaideep Srivastava Sep 1993

Entity Identification In Database Integration: An Evidential Reasoning Approach, Ee Peng Lim, Jaideep Srivastava

Research Collection School Of Computing and Information Systems

Entity identification is the problem of matching object instances from different databases which correspond to the same real-world entity. In this paper, we present a 2-step entity identification process in which attributes for matching tuples may be missing in certain tuples, and thus need to be derived prior to the matching. To match tuples, we require identity rules which specify the conditions to be satisfied by a pair of tuples, from different databases, before they can be considered as modeling the same real-world entity. We also introduce ILFD's (instance-level functional dependencies) as a form of inference rules which derive the …

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Entity Identification In Database Integration, Ee Peng Lim, Jaideep Srivastava, Satya Prabhakar, James Richardson Apr 1993

Entity Identification In Database Integration, Ee Peng Lim, Jaideep Srivastava, Satya Prabhakar, James Richardson

Research Collection School Of Computing and Information Systems

The objective of entity identification is to determine the correspondence between object instances from more than one database. Entity identification at the instance level, assuming that schema level heterogeneity has been resolved a priori, is examined. Soundness and completeness are defined as the desired properties of any entity identification technique. To achieve soundness, a set of identity and distinctness rules are established for entities in the integrated world. The use of extended key, which is the union of keys, and possibly other attributes, from the relations to be matched, and its corresponding identify rule are proposed to determine the equivalence …

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Repository Evaluation Of Software Reuse: An Empirical Study, R. D. Banker, Robert J. Kauffman, D. Zweig Jan 1993

Repository Evaluation Of Software Reuse: An Empirical Study, R. D. Banker, Robert J. Kauffman, D. Zweig

Research Collection School Of Computing and Information Systems

The use and benefits of repository evaluation of software reuse are illustrated through an analysis of the evolving repositories of two large firms that recently implemented integrated CASE development tools. The analysis shows that these tools have supported high levels of software reuse, but it also suggests that there remains considerable unexploited reuse potential. The findings indicate that organizational changes will be required before the full potential of the new technology can be realized.

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