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Multi-key index for distributed database system

INTERNATIONAL JOURNAL OF SOFTWARE ENGINEERING AND KNOWLEDGE ENGINEERING 2005年第2期15卷 433-438页

作者： Hosain, MS Newton, MAH Univ Asia Pacific CSE Dept Dhaka 1209 Bangladesh Bangladesh Univ Engn & Technol CSE Dept Dhaka 1000 Bangladesh

In this paper we present a multi-key index model that enables us to search a record with more than one attribute values in distributed database systems. Indices provide fast and efficient access of data and so become a major aspect in centralized database systems. Most of the centralized database systems use B+ tree or other types of index structures such a., bit vector, graph structure, grid file etc. But in distributed database systems no index model is found in the literature. Therefore efficient access is a major problem in distributed databases. Our proposed index model avoids the query-flooding problem of existing system and thus optimizes network bandwidth.

关键词： relational database distributed database query optimization multi-key index

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Designing a distributed database on a local area network: a methodology and decision support system

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INFORMATION AND SOFTWARE TECHNOLOGY 2000年第3期42卷 171-184页

作者： Lee, H Park, YK Jang, G Huh, SY Korea Adv Inst Sci & Technol Grad Sch Management Corp Informat Syst Lab Dongdaemoon Gu Seoul 130012 South Korea LG LCD Ltd Kangnam Gu Seoul 135280 South Korea Oracle Korea Ltd Nam Gu Ulsan 680030 South Korea Korea Adv Inst Sci & Technol Grad Sch Management Database Applicat Lab Dongdaemoon Gu Seoul 130012 South Korea

Local area networks (LANs) are important for an enterprise to hold a competitive edge. Many companies have therefore converted terminal-based computing systems to LAN-based distributed data processing systems. This paper proposes a design methodology for distributed databases connected by a LAN. Two primary objectives of the methodology are: (i) to allocate data files and workload among heterogeneous servers;and (ii) to determine the number of servers to satisfy the response time required for processing each transaction. The file and workload allocation decision is formulated as a nonlinear zero-one integer programming problem. This problem is proven to be NP-complete. A heuristic is developed to solve this problem effectively. A decision support system is implemented and an example is solved to illustrate the practical usefulness of the system. (C) 2000 Elsevier Science B.V. All rights reserved.

关键词： distributed database decision support system local area network file and workload allocation nonlinear integer programming local processing overhead server service capacity

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Speculative locking protocols to improve performance for distributed database systems

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IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 2004年第2期16卷 154-169页

作者： Reddy, PK Kitsuregawa, M Int Inst Informat Technol Hyderabad 500019 Andhra Pradesh India Univ Tokyo Inst Ind Sci Meguro Ku Tokyo 1538505 Japan

In this paper, we have proposed speculative locking (SL) protocols to improve the performance of distributed database systems (DDBSs) by trading extra processing resources. In SL, a transaction releases the lock on the data object whenever it produces corresponding after-image during its execution. By accessing both before and after-images, the waiting transaction carries out speculative executions and retains one execution based on the termination (commit or abort) mode of the preceding transactions. By carrying out multiple executions for a transaction, SL increases parallelism without violating serializability criteria. Under the naive version of SL, the number of speculative executions of the transaction explodes with data contention. By exploiting the fact that a submitted transaction is more likely to commit than abort, we propose the SL variants that process transactions efficiently by significantly reducing the number of-speculative executions. The simulation results indicate that even with manageable extra resources, these variants significantly improve-the performance over two-phase locking in the DDBS environments where transactions spend longer time for processing and transaction-aborts occur frequently.

关键词： distributed database transaction processing concurrency control locking performance evaluation speculation

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THE EFFECTS OF 2-PHASE LOCKING ON THE PERFORMANCE OF A distributed database-MANAGEMENT SYSTEM

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PERFORMANCE EVALUATION 1988年第2期8卷 129-157页

作者： THANOS, C BERTINO, E CARLESI, C CNR IST ELABORAZ INFORMAZI-56100 PISAITALY

In this paper, the effects of two-phase locking on the performance of a distributed database management system are evaluated. In particular, the relationship between the average transaction response time for four concurrency control algorithms based on two-phase locking has been established with respect to the static degree of interference for a given multiprogramming level, database size, and transaction size. The increase in average probability of one lock request conflicting with another has been measured with respect to the static degree of interference and the percentage of aborted transactions has been measured for each algorithm. In addition, the impact of a number of parameters (e.g. data replication, lock predeclaration, time-out, local processing time, degree of locality of references, interarrival time, number of nodes and transmission time) on the performance of a distributed database management system in the presence of a concurrency control mechanism has also been measured. The study has been made using simulation and the SIMULA programming language.

关键词： database distributed database Concurrency Control Two-Phase Locking Simulation

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A general fragments allocation method for join query in distributed database

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INFORMATION SCIENCES 2020年 512卷 1249-1263页

作者： Gao, Jintao Liu, Wenjie Li, Zhanhuai Zhang, Jian Shen, Li Northwestern Polytech Univ Xian 710072 Peoples R China PingCAP Ltd Beijing 100096 Peoples R China

The quality of fragments allocation is key for improving performance of join query in distributed database. Current strategies concentrate on using heuristic rules to allocate fragments to corresponding locations, such as picking the location with maximum required data or with greedy algorithm. Notwithstanding their benefits, under distributed environment, facing various query plans, different data distributions and expensive network cost, their scene-sensitive character may easily generate low quality allocation plan due to lack of generalization ability. In this paper, for breaking this limitation, we propose a general strategy for allocating fragments(AlCo, Allocate fragments based on Cost). AICo evaluates multiple candidate allocation plans based on cost, which is realized by a modified genetic algorithm employed from PostgreSQL. Our fitness function (cost model) synthetically considers various changeable factors to support generalization ability. For reducing the risks caused by randomization of genetic algorithm, AICo provides an upper bound computed through current heuristic methods to improve the robustness of our genetic algorithm. We implement AICo in a distributed database system, and the experiments show that, on TPC-H benchmark, AICo is up to 2x-4x better on performance than existing strategies and performs well in robustness and scalability. (C) 2019 Elsevier Inc. All rights reserved.

关键词： distributed database Genetic algorithm Query optimization Fragments allocation Robustness

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An Evolutionary Genetic Algorithm for Optimization of distributed database Queries

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COMPUTER JOURNAL 2011年第5期54卷 717-725页

作者： Sevinc, Ender Cosar, Ahmet Middle E Tech Univ Dept Comp Engn TR-06531 Ankara Turkey

High-performance low-cost PC hardware and high-speed LAN/WAN technologies make distributed database (DDB) systems an attractive research area where query optimization and DDB design are the two important and related problems. Since dynamic programming is not feasible for optimizing queries in a DDB, we propose a new genetic algorithm (GA)-based query optimizer (new genetic algorithm (NGA)) and compare its performance with random and optimal (exhaustive) algorithms. We perform experiments on a synthetic database with replicated relations, but no horizontal or vertical fragmentation. Network links are assumed to be gigabit ethernet. Comparisons with optimal results show that our NGA formulation performs only 20% of the optimal results and we have achieved 50% improvement over a previous GA-based algorithm.

关键词： query optimization distributed database genetic algorithm

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DEVELOPMENT OF DATA-FREE-WAY distributed database SYSTEM FOR ADVANCED NUCLEAR-MATERIALS

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JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 1994年第12期31卷 1314-1324页

作者： UENO, F KANO, S FUJITA, M KURIHARA, Y NAKAJIMA, H YOKOYAMA, N IWATA, S NATL RES INST MET TSUKUBA 305 JAPAN JAPAN ATOM ENERGY RES INST TOKAI IBARAKI 31911 JAPAN UNIV TOKYO BUNKYO KU TOKYO 113 JAPAN

A distributed database system named ''Data-Free-Way (DFW)'' is under development by a cooperation among three Japanese national research organizations to support the creation of advanced nuclear materials. The development of DFW started in 1990 as a five-year program with a support from Science and Technology Agency of Japan. Before starting the program, a preliminary survey of both domestic and foreign databases of nuclear materials had been made for two years. Then, subjects for the construction of DFW were extracted. To meet the subjects, the development and construction programs were established. The DFW is constructed on the computer network which connects engineering workstations in the separate organizations. A relational database management system is used, a distributed material database is equipped on the hardware with specially designed common data structure. Data storage has been carried out continuously in each organization. The equipment of useful user-interface systems, such as retrieval, data entry and process supporting and image data handling systems, have also been constructed to make it friendly for users. The collection of nuclear material data from three research organizations and its mutual usage have become possible by the construction of DFW.

关键词： distributed database ADVANCED NUCLEAR MATERIAL USER-INTERFACE DATA STRUCTURE ENGINEERING WORKSTATION database MANAGEMENT SYSTEM COMPUTER NETWORK RETRIEVAL SYSTEM IMAGE DATA

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AN ALGORITHM FOR NON-INTERFERING CHECKPOINTS AND ITS PRACTICALITY IN distributed database-SYSTEMS

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INFORMATION SYSTEMS 1989年第5期14卷 421-429页

作者： SON, SH Department of Computer Science University of Virginia Charlottesville VA 22903 U.S.A.

The goal of checkpointing in database management systems is to save database states on a separate secure device so that the database can be recovered when errors and failures occur. Recent study shows the possibility of a checkpointing mechanism that does not interfere with the transaction processing, and yet achieves the global consistency of the checkpoints. The motivation of non-interfering checkpointing is to improve the system availability. Although the property of non-interference is highly desirable in many applications of distributed database systems, where restricting transaction activity during the checkpointing operation is not feasible, it makes checkpointing complicated and increases the workload of the system. In this paper, we study the practicality of a non-interfering checkpointing algorithm by analyzing the extra workload of the system

关键词： distributed database checkpoint consistency recovery non-interference

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OPTIMAL SEMIJOINS FOR distributed database-SYSTEMS

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IEEE TRANSACTIONS ON SOFTWARE ENGINEERING 1990年第5期16卷 558-560页

作者： MULLIN, JK Department of Computer Science University of Western Ontario London Canada

A Bloom filter based semijoin algorithm for distributed database systems is presented. This algorithm reduces communications costs to process a distributed natural join as much as possible with a filter approach. An optimal filter is developed in pieces. Filter information is used both to recognize when the semijoin will cease to be effective and to optimally process the semijoin. An ineffective semijoin will be quickly and cheaply recognized. An effective semijoin will use all of the transmitted bits optimally. No other known method can achieve lower communications cost. [ABSTRACT FROM AUTHOR]

关键词： Bloom filter distributed database distributed systems natural join semijoin

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USING PREDICATE-TRANSITION-NETS TO MODEL AND ANALYZE distributed database-SYSTEMS

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IEEE TRANSACTIONS ON SOFTWARE ENGINEERING 1980年第6期6卷 539-544页

作者： VOSS, K Institut fuer Informationssystemforschung Gesellschaft fuer Mathematik und Datenverarbeitung

In this paper, a net model for decentralized control of user accesses to a distributed database is proposed. It is developed in detail for the restricted case of updating distributed copies of a single database. Predicate/transition-nets, a first-order extension of Petri nets, are shown to provide suitable means for concise representation of complex decentralized systems and for their rigorous formal analysis. It will be demonstrated in the present paper how these net models can be constructed and interpreted in a quite natural manner and how they can be analyzed by linear algebraic methods. By this, it will be shown that the modeled distributed database system is deadlock-free and guarantees a consistent database as well as a fair and effective service to the users.

关键词： Synchronization Concurrency Consistency database Management Deadlock Free Decentralized Control distributed database distributed Processing Petri Nets Predicate Transition Nets

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