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Efficient distributed Skyline Queries for Mobile Applications

计算机科学技术学报（英文版） 2010年第3期25卷 523-536页

作者： Ying-Yuan Xiao Yue-Guo Chen Tianjin Key Laboratory of Intelligence Computing and Novel Software Technology Tianjin University of Technology Tianjin 300191China Key Laboratory of Computer Vision and System Tianjin University of TechnologyTianjin 300191China School of Computing National University of Singapore117417Singapore Key Laboratory of Data Engineering and Knowledge Engineering Renmin University of ChinaBeijing 100872China

In this paper,we consider skyline queries in a mobile and distributed environment,where data objects are distributed in some sites(database servers)which are interconnected through a high-speed wired network,and queries are issued by mobile units(laptop,cell phone,etc.)which access the data objects of database servers by wireless *** inherent properties of mobile computing environment such as mobility,limited wireless bandwidth,frequent disconnection,make skyline queries more *** show how to efficiently perform distributed skyline queries in a mobile environment and propose a skyline query processing approach,called efficient distributed skyline based on mobile computing(EDS-MC).In EDS-MC,a distributed skyline query is decomposed into five processing phases and each phase is elaborately designed in order to reduce the network communication,network delay and query response *** conduct extensive experiments in a simulated mobile database system,and the experimental results demonstrate the superiority of EDS-MC over other skyline query processing techniques on mobile computing.

关键词： skyline distributed query processing mobile database system

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Scalable distributed processing of K Nearest Neighbor Queries over Moving Objects

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IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 2015年第5期27卷 1383-1396页

作者： Yu, Ziqiang Liu, Yang Yu, Xiaohui Pu, Ken Q. Shandong Univ Sch Comp Sci & Technol Jinan 250101 Shandong Peoples R China York Univ Sch Informat Technol Toronto ON M3J 2R7 Canada Univ Ontario Inst Technol Fac Sci Oshawa ON Canada

Central to many applications involving moving objects is the task of processing k-nearest neighbor (k-NN) queries. Most of the existing approaches to this problem are designed for the centralized setting where query processing takes place on a single server;it is difficult, if not impossible, for them to scale to a distributed setting to handle the vast volume of data and concurrent queries that are increasingly common in those applications. To address this problem, we propose a suite of solutions that can support scalable distributed processing of k-NN queries. We first present a new index structure called Dynamic Strip Index (DSI), which can better adapt to different data distributions than exiting grid indexes. Moreover, it can be naturally distributed across the cluster, therefore lending itself well to distributed processing. We further propose a distributed k-NN search (DKNN) algorithm based on DSI. DKNN avoids having an uncertain number of potentially expensive iterations, and is thus more efficient and more predictable than existing approaches. DSI and DKNN are implemented on Apache S4, an open-source platform for distributed stream processing. We perform extensive experiments to study the characteristics of DSI and DKNN, and compare them with three baseline methods. Experimental results show that our proposal scales well and significantly outperforms the alternative methods.

关键词： k nearest neighbor query distributed query processing moving objects

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IrisNet: An architecture for a worldwide sensor web

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IEEE PERVASIVE COMPUTING 2003年第4期2卷 22-33页

作者： Gibbons, PB Karp, B Ke, Y Nath, S Seshan, S Intel Res Pittsburgh Pittsburgh PA USA Carnegie Mellon Univ Dept Comp Sci Pittsburgh PA 15213 USA

Today's common computing hardware-Internet connected desktop PCs and inexpensive, commodity off-the-shelf sensors such as Webcams-is an ideal platform for a worldwide sensor web. IrisNet provides a software infrastructure for this platform that lets users query globally distributed collections of high-bit-rate sensors powerfully and efficiently.

关键词： Sensor Networks distributed Computing Wide Area Sensing Worldwide Sensor Web distributed query processing

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Management of distributed knowledge encapsulated in embedded devices

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INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2016年第18期54卷 5434-5451页

作者： Ferrer, Borja Ramis Iarovyi, Sergii Gonzalez, Luis Lobov, Andrei Lastra, Jose L. Martinez Tampere Univ Technol Factory Automat Syst & Technol Lab FAST Lab Tampere Finland

Embedded electronic devices are now to be found everywhere. In general, they can be used to collect different sorts of data (e.g. on temperature, humidity, illumination and locations). In some specific domains, such as industrial automation, embedded devices are used for process control. The devices may have a programme that can respond immediately to environmental changes perceived through sensors. In the control of large sites, where there are many devices, higher level decisions are made or processed in dedicated computers far away from the sources (devices) where the initial data are collected. This article shows how it is possible to manage portions of distributed knowledge, hosted in embedded devices, making it possible for each embedded device to hold and manage its piece of knowledge. In addition, presented approach allows keeping locus of control at the embedded device level, where the embedded device can make decisions knowing the status of the rest of the world, device contributions and their effects in the overall distributed system knowledge base.

关键词： knowledge-based systems ontologies distributed knowledge bases distributed query processing industrial automation

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Join of Multiple Data Streams in Sensor Networks

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IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 2009年第12期21卷 1722-1736页

作者： Zhu, Xianjin Gupta, Himanshu Tang, Bin Microsoft Inc Seattle WA USA SUNY Stony Brook Dept Comp Sci Stony Brook NY 11794 USA Wichita State Univ Dept Elect Engn & Comp Sci Wichita KS 67260 USA

Sensor networks are multihop wireless networks of resource-constrained sensor nodes used to realize high-level collaborative sensing tasks. To query or access data generated by the sensor nodes, the sensor network can be viewed as a distributed database. In this paper, we develop algorithms for communication-efficient implementation of join of multiple (two or more) data streams in a sensor network. The distributed implementation of join in sensor networks is particularly challenging due to unique characteristics of the sensor networks such as limited memory and battery energy on individual nodes, arbitrary and dynamic network topology, multihop communication, and unreliable infrastructure. One of our proposed approaches, viz., the Perpendicular Approach (PA), is load balanced, and in fact, incurs near-optimal communication cost for the special case of binary joins in grid networks under the assumption of uniform generation of tuples across the network. We compare the performance of our designed approaches through extensive simulations on the ns2 simulator, and show that PA results in substantially prolonging the network lifetime compared to other approaches, especially for joins involving spatial constraints.

关键词： distributed query processing Sensor networks

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query Planning for Continuous Aggregation Queries over a Network of Data Aggregators

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IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 2012年第6期24卷 1065-1079页

作者： Gupta, Rajeev Ramamritham, Krithi IBM India Private Ltd 4 IBM Res Inst Area New Delhi 110070 India Indian Inst Technol Dept Comp Sci & Engn Bombay 400076 Maharashtra India

Continuous queries are used to monitor changes to time varying data and to provide results useful for online decision making. Typically a user desires to obtain the value of some aggregation function over distributed data items, for example, to know value of portfolio for a client;or the AVG of temperatures sensed by a set of sensors. In these queries a client specifies a coherency requirement as part of the query. We present a low-cost, scalable technique to answer continuous aggregation queries using a network of aggregators of dynamic data items. In such a network of data aggregators, each data aggregator serves a set of data items at specific coherencies. Just as various fragments of a dynamic webpage are served by one or more nodes of a content distribution network, our technique involves decomposing a client query into subqueries and executing subqueries on judiciously chosen data aggregators with their individual subquery incoherency bounds. We provide a technique for getting the optimal set of subqueries with their incoherency bounds which satisfies client query's coherency requirement with least number of refresh messages sent from aggregators to the client. For estimating the number of refresh messages, we build a query cost model which can be used to estimate the number of messages required to satisfy the client specified incoherency bound. Performance results using real-world traces show that our cost-based query planning leads to queries being executed using less than one third the number of messages required by existing schemes.

关键词： Algorithms continuous queries distributed query processing data dissemination coherency performance

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Estimating the quality of answers when querying over description logic ontologies

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DATA & KNOWLEDGE ENGINEERING 2003年第1期47卷 105-129页

作者： Peim, M Franconi, E Paton, NW Univ Manchester Dept Comp Sci Manchester M13 9PL Lancs England Free Univ Bolzano I-39100 Bolzano Italy

Information integration systems allow users to express queries over high-level conceptual models. However, such queries must subsequently be evaluated over collections of sources, some of which are likely to be expensive to use or subject to periods of unavailability. As such, it would be useful if information integration systems were able to provide users with estimates of the consequences of omitting certain sources from query execution plans. Such omissions can affect both the soundness (the fraction of returned answers which are returned) and the completeness (the fraction of correct answers which are returned) of the answer set returned by a plan. Many recent information integration systems have used conceptual models expressed in description logics (DLs). This paper presents an approach to estimating the soundness and completeness of queries expressed in the ALCQI DL. Our estimation techniques are based on estimating the cardinalities of query answers. We have have conducted some statistical evaluation of our techniques, the results of which are presented here. We also offer some suggestions as to how estimates for cardinalities of subqueries can be used to aid users in improving the soundness and completeness of query plans. (C) 2003 Elsevier B.V. All rights reserved.

关键词： data quality cardinality estimation description logics distributed query processing information integration

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processing distributed mobile queries with interleaved remote mobile joins

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IEEE TRANSACTIONS ON COMPUTERS 2002年第10期51卷 1182-1195页

作者： Lee, CH Chen, MS Natl Taiwan Univ Dept Elect Engn Taipei 10764 Taiwan

The query processing in a mobile computing environment involves join processing among different sites which include static servers and mobile computers. Because of the presence of asymmetric features in a mobile computing environment, the conventional query processing for a distributed database cannot be directly applied to a mobile computing system. In this paper, we first explore some unique features of a mobile environment and then, in light of these features, devise query processing methods for both join and query processing. Remote mobile joins are said to be effectual if they are, when being interleaved into a join sequence, able to reduce the amount of data transmission cost required for distributed mobile query processing. Since mobile relations are employed as reducers in our proposed query processing cost model, more mobile joins in the query processing lead to less data transmitted through the network. With proper scheduling, interleaving effectual remote mobile joins into a query scheduling can significantly reduce the total amount of data transmission among different sites. A simulator is developed to evaluate the performance of algorithms devised. Our results show that the approach of interleaving the processing of distributed mobile queries with effectual remote mobile joins is not only efficient, but also effective in reducing the total amount of data transmission cost required to process distributed mobile queries.

关键词： distributed query processing mobile computing remote mobile joins query scheduling

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A service-oriented system for distributed data querying and integration on Grids

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FUTURE GENERATION COMPUTER SYSTEMS-THE INTERNATIONAL JOURNAL OF ESCIENCE 2009年第5期25卷 511-524页

作者： Comito, Carmela Gounaris, Anastasios Sakellariou, Rizos Talia, Domenico Univ Calabria DEIS I-87036 Arcavacata Di Rende Italy Aristotle Univ Thessaloniki Dept Informat Thessaloniki 54124 Greece Univ Manchester Sch Comp Sci Manchester M13 9PL Lancs England

Data Grids rely on the coordinated sharing of and interaction across multiple autonomous database management systems. They provide transparent access to heterogeneous and autonomous data resources stored on Grid nodes. Data sharing tools for Grids must include both distributed query processing and data integration functionality. This paper presents the implementation of a data sharing system that (i) is tailored to data Grids, (ii) supports well established and widely spread relational DBMSs, and (iii) adopts a hybrid architecture by relying on a peer model for query reformulation to retrieve semantically equivalent expressions, and on a wrapper-mediator integration model for accessing and querying distributed data sources. The system builds upon the infrastructure provided by the OGSA-DQP distributed query processor and the XMAP query reformulation algorithm. The paper discusses the implementation methodology, and presents empirical evaluation results. (C) 2008 Elsevier B.V. All rights reserved.

关键词： Data Grids distributed query processing Wide-area data integeration OGSA-DQP XMAP

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distributed DATABASE-SYSTEMS - WHERE ARE WE NOW

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COMPUTER 1991年第8期24卷 68-78页

作者： OZSU, MT VALDURIEZ, P GTE LABS INC WALTHAMMA 02254 INST NATL RECH INFORMAT & AUTOMAT F-78153 LE CHESNAYFRANCE

The authors explain what is meant by a distributed database system and discuss its characteristics. They survey the state of distributed database technology, focusing on how well products meet the goals of transparent management of distributed and replicated data, reliability through distributed transactions, better performance, and easier, more economical system expansion. They then consider unsolved problems with regard to network scaling, distribution design, distributed query processing, distributed transaction processing, integration with distributed operating systems, and distributed multidatabase systems

关键词： distributed database system distributed databases distributed multidatabase systems distributed operating systems distributed query processing distributed transaction processing distribution design network operating systems network scaling query languages replicated data transaction processing

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