检索结果-内蒙古大学图书馆

A scheduling of database migration in wide‐area networks

Systems and Computers in Japan 2000年第10期31卷 10-19页

作者： Takahiro Hara Masahiko Tsukamoto Shojiro Nishio Department of Information Systems Engineering Graduate School of Engineering Osaka University Suita 565-0871 Department of Information Systems Engineering Graduate School of Engineering Osaka University Suita 565-0871 Department of Information Systems Engineering Graduate School of Engineering Osaka University Suita 565-0871

In broadband networks, appropriate use of database migration can drastically shorten the transaction processing time of a distributed database system. So far, we have proposed a transaction processing method based on database migration, where we have assumed that the network bandwidth is almost uniform and very broad over a whole network. However, WANs consist of various types of networks such as private LANs, narrowband public networks, and broadband backbones, and thus, it is difficult to control database migration in the granularity of the transaction and to execute database migration through networks other than backbones. Therefore, the proposed method cannot be used directly in such heterogeneous WAN environments. In this paper, we propose a scheduling method of database migration, which gives the shortest communication time for database operations, assuming that database migration is used in such heterogeneous WANs. We also discuss an implementation method of our proposed scheduling method in a practical environment. © 2000 Scripta Technica, Syst Comp Jpn, 31(10): 10-19, 2000

关键词： database migration WAN (wide‐area network) broadband network distributed database

来源：评论

学校读者我要写书评

暂无评论

Large scale distributed data repository: design of a molecular dynamics trajectory database

引用

FUTURE GENERATION COMPUTER SYSTEMS 1999年第1期16卷 101-110页

作者： Feig, M Abdullah, M Johnsson, L Pettitt, BM Univ Houston Dept Chem Houston TX 77204 USA Univ Houston Inst Mol Design Houston TX 77204 USA Univ Houston Dept Comp Sci Houston TX 77204 USA

The design of a molecular dynamics trajectory database is presented as an example of the organization of large-scale dynamic distributed repositories for scientific data. Large scientific datasets are usually interpreted through reduced data calculated by analysis functions. This allows a database architecture in which the analyzed datasets, that are kept in addition to the raw datasets, are transferred to a database user. A flexible user interface with a well defined Application Program Interface (API) allows for a wide array of analysis functions and the incorporation of user defined functions is a critical part of the database design. An analysis function is executed only when the requested analysis result is not available from an earlier request. A prototype implementation used to gain initial practical experiences with performance and scalability is presented. (C) 1999 Elsevier Science B.V. All rights reserved.

关键词： distributed database scientific data archive data analysis

来源：评论

学校读者我要写书评

暂无评论

基于分布式数据库的远程教育系统

基于分布式数据库的远程教育系统

引用

第十七届全国数据库学术会议

作者：杨乔苟重庆建筑大学计算机科学系

1引言自从Internet出现以来,它正以惊人的速度,向世界各地、各个行业扩展渗透,其中远程教育(DistanceEducation)就是应用Internet的典型范例之一。"远程教育"是指异地间通过电信和信息处理技术提供信息存储和处理手段,以及传... 详细信息

1引言自从Internet出现以来,它正以惊人的速度,向世界各地、各个行业扩展渗透,其中远程教育(DistanceEducation)就是应用Internet的典型范例之一。"远程教育"是指异地间通过电信和信息处理技术提供信息存储和处理手段,以及传送声音、数据、文件、图片,甚至活动和彩色图像的教育活动。基于Internet的远程教育要求具备:视频图像、语音实时传送、文字资料传送,以及教育影像传输的功能。远程教育与传统的教育相比,有投资少、见效快、覆盖面大等许多优点。从80年代到现在,经过了20多年的发展,局域网技术

关键词： distributed database Internet Distance Education System

来源：评论

学校读者我要写书评

暂无评论

军区器材分布式数据库系统的网络管理及其数据信息查询

军区器材分布式数据库系统的网络管理及其数据信息查询

引用

第十七届全国数据库学术会议

作者：叶新铭宋艳王玉清内蒙古大学计算机学院

1引言在二十一世纪中,"信息化革命"迅猛发展,计算机信息技术在各个领域的应用带来了社会的巨大进步。同样,军事上计算机技术的应用,使得军事力量建设更加正规化、自动化,从而加强了国防力量的建设。在信息化建设方面,我国军... 详细信息

1引言在二十一世纪中,"信息化革命"迅猛发展,计算机信息技术在各个领域的应用带来了社会的巨大进步。同样,军事上计算机技术的应用,使得军事力量建设更加正规化、自动化,从而加强了国防力量的建设。在信息化建设方面,我国军队中器材管理技术严重落后于外国军队的建设,针对这种情况,本文结合

关键词： distributed database QOS Semi-Structured Data Optimal Query SQL

来源：评论

学校读者我要写书评

暂无评论

A hierarchical commitment algorithm for permanent time stamp ordering

引用

Systems and Computers in Japan 2000年第12期31卷

作者： Shin-ya Kobayashi Kouji Matsuura Nobuyuki Ishimori Munehiro Fukuda Faculty of Engineering Kanazawa University Kanazawa Japan 920-8667 Institute of Information Sciences and Electronics University of Tsukuba Tsukuba Japan 305-8576

One of the concurrent execution control schemes in distributed database systems is the permanent time stamp method, in which the order of the requests can be followed. The method provides two phases of commitment control: precommitment and true commitment. In the acknowledgment of true commitment, the global processing minimum time stamp (GTA), which is the minimum value of the time stamps for the processing transactions in the system, is used. Methods proposed for the determination of the GTA include a method based on circulating tokens [1] and the method in which the decision is made centrally in the control node [2]. This paper proposes a method in which the nodes are logically connected in a tree structure, and the GTA is determined by the root node, to which the local minimum values of the time stamps for the transactions being processed are sent from each node. It is shown that the root node can determine the correct GTA by the proposed method and that the GTA is always increasing. © 2000 Scripta Technica, Syst Comp Jpn, 31(12): 83–92, 2000

关键词： distributed database concurrent execution control permanent time stamp method proof of validity

来源：评论

学校读者我要写书评

暂无评论

A dynamic replica allocation method based on database migration in broadband networks

引用

Systems and Computers in Japan 2000年第8期31卷

作者： Takahiro Hara Kaname Harumoto Masahiko Tsukamoto Shojiro Nishio Jun Okui Department of Information Systems Engineering Graduate School of Engineering Osaka University Suita Japan 565-0871 Department of Electronic Systems and Information Engineering Faculty of Biology-Oriented Science and Technology Kinki University Wakayama Japan 649-6493

Dynamic relocation of databases through networks, or database migration, will soon become a powerful standard database operation effectively using recent advances in broadband networks. In our previous work, a transaction processing method has been proposed in distributed database environments, based on database migration operations. Generally, database replication is an effective technique to improve transaction processing throughput in conventional systems. In this paper, we propose a replica management method for use with database migration. database migration is used at the beginning of a transaction to dynamically relocate database replicas. The performance of the proposed method is evaluated using simulation results. © 2000 Scripta Technica, Syst Comp Jpn, 31(8): 22–32, 2000

关键词： database migration database replication broadband network distributed database

来源：评论

学校读者我要写书评

暂无评论

A one-phase algorithm to detect distributed deadlocks in replicated databases

引用

IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 1999年第6期11卷 880-895页

作者： Kshemkalyani, AD Singhal, M Univ Illinois Dept Elect Engn & Comp Sci Chicago IL 60607 USA Ohio State Univ Dept Comp & Informat Sci Columbus OH 43210 USA

Replicated databases that use quorum-consensus algorithms to perform majority voting are prone to deadlocks. Due to the P-out-of-Q nature of quorum requests, deadlocks that arise are generalized deadlocks and are hard to detect. We present an efficient distributed algorithm to detect generalized deadlocks in replicated databases. The algorithm performs reduction of a distributed wait-for-graph (WFG) to determine the existence of a deadlock. If sufficient information to decide the reducibility of a node is not available at that node, the algorithm attempts reduction later in a lazy manner. We prove the correctness of the algorithm. The algorithm has a message complexity of 2e messages and a worst-case time complexity of 2d + 2 hops, where e is the number of edges and d is the diameter of the WFG. The algorithm is shown to perform significantly better in both time and message complexity than the best known existing algorithms. We conjecture that this is an optimal algorithm, in time and message complexity, to detect generalized deadlocks it no transaction has complete knowledge of the topology of the WFG or the system and the deadlock detection is to be carried out in a distributed manner.

关键词： distributed database replicated database quorum consensus generalized deadlock graph reduction

来源：评论

学校读者我要写书评

暂无评论

MODEC: A multi-granularity mobile object-oriented database caching mechanism, prototype and performance

引用

distributed AND PARALLEL databaseS 1999年第3期7卷 343-372页

作者： Chan, BYL Leong, HV Si, A Wong, KF Hong Kong Polytech Univ Dept Comp Hong Kong Peoples R China Sun Microsyst Inc Palo Alto CA 94303 USA

An inherent limitation in mobile data access is due to the unreliable and low bandwidth wireless communication channel. Caching of useful database items from database server in local storage of mobile clients is effective in reducing data access latency and wireless bandwidth consumption. In the event of disconnection, cached data can also serve the purpose of partial query processing. In this paper, we present the implementation and evaluate a new caching mechanism for object-oriented database systems in a mobile environment called MODEC. MODEC possesses the capabilities of performing caching at multiple granularities and adapting to changes in data access pattern, providing improved performance through tolerating limited inconsistency to read-only transactions. This caching capabilities is supported via standard ODMG modeling constructs. The prototype of MODEC is implemented using ODE database. Empirical system performance results are obtained from experiments on the prototype with data from a real-life database. The results are validated against results obtained via detailed simulation studies on MODEC. Both sets of results are found to be consistent and are in favor of our MODEC mechanism in providing a feasible solution to the mobile data access problem under the constraints in a mobile environment.

关键词： mobile data access distributed database multi-granularity caching cache replacement cache refreshing

来源：评论

学校读者我要写书评

暂无评论

Incremental view maintenance by base relation tagging in distributed databases

引用

distributed AND PARALLEL databaseS 1998年第3期6卷 287-309页

作者： Bailey, J Dong, GZ Mohania, M Wang, XS Univ London Kings Coll Dept Comp Sci London WC2R 2LS England Univ Melbourne Dept Comp Sci Parkville Vic 3052 Australia Univ S Australia Sch Informat & Comp Sci Mawson Lakes 5095 Australia George Mason Univ Dept Informat & Software Syst Engn Fairfax VA 22030 USA

The incremental view maintenance problem deals with the efficient updating of materialized views in response to updates to base relations. This paper considers the problem in a distributed database environment, with communication cost minimization as the primary objective. The views considered are defined based on the relational join operation. The approach is to use "yes"/"no" tags as auxiliary data on tuples in the base relations to indicate whether the tuples participate in joins. These tags will help avoid sending irrelevant data over the network and thus reduce the communication cost. Two basic view maintenance algorithms are proposed using the tags. In addition to reducing communication costs, an important feature of these two basic algorithms is that they derive the "exact change" to views without looking at the old views. This feature allows us to maintain certain aggregates on views without actually materializing the views themselves;this feature is useful in applications such as active databases where many conditions or constraints must be tested whenever updates occur, since a condition is true exactly when some corresponding view has nonzero number of tuples. The paper then combines the use of tags with the counting algorithm to derive a tagged counting algorithm that further reduces the communication cost. The paper illustrates the algorithms by examples and studies their performance via a statistical analysis. The illustrating examples and the performance analysis show that, under uniform distribution with reasonable join participation rates, the use of tags significantly improves the efficiency of view maintenance over similar algorithms without tags. The performance analysis also identifies the situations where a particular algorithm is superior to others. The use of tags for memoing values of subexpressions in a view definition is also explored in the paper.

关键词： distributed database view maintenance auxiliary data structure base relation tagging exact change

来源：评论

学校读者我要写书评

暂无评论

Competitive analysis of caching in distributed databases

引用

IEEE TRANSACTIONS ON PARALLEL AND distributed SYSTEMS 1998年第4期9卷 391-409页

作者： Wolfson, O Huang, YX Univ Illinois Dept Elect Engn & Comp Sci Chicago IL 60607 USA

This paper makes two contributions. First, we introduce a model for evaluating the performance of data allocation and replication algorithms in distributed databases. The model is comprehensive in the sense that it accounts for I/O cost, for communication cost, and, because of reliability considerations, for limits on the minimum number of copies of the object. The model captures existing replica-management algorithms, such as read-one-write-all, quorum-consensus, etc. These algorithms are static in the sense that, in the absence of failures,, the copies of each object are allocated to a fixed set of processors. In modern distributed databases, particularly in mobile computing environments, processors will dynamically store objects in their local database and will relinquish them. Therefore, as a second contribution of this paper, we introduce an algorithm for automatic dynamic allocation of replicas to processors. Then, using the new model, we compare the performance of the traditional read-one-write-all static allocation algorithm to the performance of the dynamic allocation algorithm. As a result, we obtain the relationship between the communication cost and I/O cost for which static allocation is superior to dynamic allocation, and the relationships for which dynamic allocation is superior.

关键词： object allocation caching distributed database mobile computing wireless communication competitiveness

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：