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CHECKPOINTING FOR distributed databaseS - STARTING FROM THE BASICS

IEEE TRANSACTIONS ON PARALLEL AND distributed SYSTEMS 1992年第5期3卷 602-610页

作者： PILARSKI, S KAMEDA, T School of Computing Science Simon Fraser University Burnaby BC Canada

This paper first analyzes checkpointing in a distributed database system by establishing a correspondence between consistent snapshots in a general distributed system and transaction-consistent checkpoints in a distributed database system. Our analysis culminates in a useful condition for transaction-consistent checkpoints. Based on this condition, we then present a general checkpointing scheme, which records a transaction-consistent set of values of all or some selected data items. Finally we implement these rules in some representative concurrency control protocols, i.e., those based on two-phase locking and timestamping. These implementations cause little interference with other activities in the database system.

关键词： CHECKPOINTING CONCURRENCY CONTROL CONSISTENCY distributed database RECOVERY SNAPSHOT TRANSACTION

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ANALYSIS OF CONCURRENCY COHERENCY CONTROL PROTOCOLS FOR distributed TRANSACTION PROCESSING SYSTEMS WITH REGIONAL LOCALITY

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IEEE TRANSACTIONS ON SOFTWARE ENGINEERING 1992年第10期18卷 899-914页

作者： CICIANI, B DIAS, DM YU, PS IBM CORP THOMAS J WATSON RES CTRDIV RESYORKTOWN HTSNY 10598

In this paper we examine a system structure and protocols to improve the performance of a distributed transaction processing system when there is some regional locality of data reference. Several transaction processing applications such as reservation systems, insurance, and banking belong to this category. While maintaining a distributed computer system at each region, a central computer system is introduced with a replication of all databases at the distributed sites. It can provide the advantage of distributed systems for transactions that refer principally to local data, and also can provide the advantage of centralized systems for transactions accessing nonlocal data. Specialized protocols can be designed to keep the copies at the distributed and centralized systems consistent without incurring the overhead and delay of generalized protocols for fully replicated databases. In this paper we study the advantage achievable through this system structure and the trade-offs between protocols for concurrency and coherency control of the duplicate copies of the databases. An approximate analytic model is employed to estimate the system performance. It is found that the performance is indeed sensitive to the protocol and substantial performance improvement can be obtained as compared with distributed systems. The protocol design factors considered include the approach for intersite concurrency control (optimistic versus pessimistic), resolution of aborts due to intersite conflict, and choice of the master/primary site of the dual copies (distributed site versus central site). Among the protocols considered, the most robust one uses an optimistic protocol for intersite control with the distributed site as the master site, allows a locally running transaction to commit without any communication with the central site, and balances transaction aborts between transactions running at the central site and distributed sites.

关键词： ANALYTIC MODEL CONCURRENCY CONTROL DATA REPLICATION distributed database PERFORMANCE ANALYSIS TRANSACTION PROCESSING

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DECIDING TO CORRECT distributed QUERY-PROCESSING

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IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 1992年第3期4卷 253-265页

作者： BODORIK, P RIORDON, JS PYRA, JS PRIOR DATA SCI LTD HALIFAX B3J 3T2NSCANADA CARLETON UNIV OTTAWA K1S 5B6ONTARIOCANADA

Most algorithms for determining query processing strategies in distributed databases are static in nature;that is, the strategy is completely determined on the basis of a priori estimates of the size of intermediate results, and it remains unchanged throughout its execution. The static approach may be far from optimal because it denies the opportunity to reschedule operations if size estimates are found to be inaccurate. Adaptive query execution may be used to alleviate this problem. This paper proposes a low overhead delay method to decide when to correct a strategy. Sampling is used to estimate the size of relations, and alternative heuristic strategies prepared in a background mode are used to decide when to correct. Evaluation using a model of a distributed database indicates that the heuristic strategies are near optimal. Moreover, it also suggests that it is usually correct to abort creation of an intermediate relation which is much larger than predicted.

关键词： distributed database ADAPTIVE QUERY PROCESSING CORRECTING QUERY PROCESSING STRATEGY STRATEGY EXECUTION PHASES OVERHEAD SIZE ESTIMATION SAMPLING PERFORMANCE EVALUATION

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THE EMBNET PROJECT - EUROPEAN MOLECULAR-BIOLOGY NETWORK

COMPUTER NETWORKS AND ISDN SYSTEMS

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COMPUTER NETWORKS AND ISDN SYSTEMS 1992年第4-5期25卷 464-468页

作者： DOELZ, R UNIV BASEL BIOZENTRUMCH-4056 BASELSWITZERLAND

The European Molecular Biology network (EMBnet) seeks to provide a communications infrastructure, access to research data and support for biocomputing research. Furthermore, new topics in this area are to be stimulated by providing a communication and education forum. The network currently consists of 17 nodes. The implementation uses mainly protocols of the IP family. International services consist of a daily database update and a mailing list which has been operated for several years to synchronize the organization. Services covering both national and international needs are the operation of ARCHIE, WAIS, FTP and GOPHER WWW servers. National services typically include access to major sequence databases and analysis software on the national networks (TCP/IP, DECNet, X.25 or direct dial). Current EMBnet projects cover the improvement of data exchange and services.

关键词： USER SUPPORT USER EDUCATION distributed RESOURCES distributed database BIOLOGICAL SEQUENCE DATA EMBNET DNA SEQUENCE DATA EMBL database CONFERENCING SYSTEMS GOPHER WAIS FTP SERVER

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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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A design model of distributed database in real-time control

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Annual Review in Automatic Programming 1990年第PART 1期15卷 53-56页

作者： Fang, Bin Peng Tian Qiang China

The problem of traditional distributed database implementation in real-time control is discussed. According to features of data in real-time control distributed system, a enhanced performance design model (EPADM) of distributed database control is presented. Lastly, measurement analysis and some appraizement on EPADM is gived. © 1990.

关键词： comumnication network data distributity distributed control system distributed database enhanced performance design real-time control

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A Design Model of distributed database in Real-Time Control

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IFAC Proceedings Volumes 1990年第4期23卷 53-56页

作者： Fang Bin Peng Tian Qiang Automation Research Institute of Metallurgical Ministry Beijing PRC

关键词： distributed control system distributed database real-time control data distributity communication network enhanced performance design

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TRANSACTIONS AND VERSIONING IN AN ODBMS

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COMPUTER STANDARDS & INTERFACES 1991年第1-3期13卷 243-248页

作者： ROTZELL, K VERSANT OBJECT TECHNOL PROD MKTMENLO PKCA 94025

Versant Object Technology builds and sells a distributed Object database Management System (ODBMS), called VERSANT. This position paper proposes transaction model and version model requirements in support of the kinds of distributed database processing that ODBMS applications require. Transaction model requirements address the long transactions required by many ODBMS applications, as well as the short transactions found in conventional DBMS products. Version model requirements suggest a minimal set of primitives which can be extended to support emerging standards and companies' specific models.

关键词： CHANGE MANAGEMENT distributed database OBJECT-ORIENTED database TRANSACTION MODEL VERSION MODEL VERSIONING

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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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ON ROBUST TRANSACTION ROUTING AND LOAD SHARING

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ACM TRANSACTIONS ON database SYSTEMS 1991年第3期16卷 476-512页

作者： YU, PS LEFF, A LEE, YH COLUMBIA UNIV DEPT COMP SCINEW YORKNY 10027 UNIV FLORIDA DEPT COMP & INFORMAT SCIGAINESVILLEFL 32611

In this paper we examine the issue of robust transaction routing in a locally distributed database environment where transaction characteristics such as reference locality imply that certain processing systems can be identified as being more suitable than others for a given transaction class. A response time based routing strategy can strike a balance between indiscriminate sharing of the load and routing based only on transaction affinity. Since response time estimates depend on workload and system parameters that may not be readily available, it is important to examine the robustness of routing decisions to information accuracy. We find that a strategy which strictly tries to minimize the response time of incoming transactions is sensitive to the accuracy of certain parameter values. On the other hand, naive strategies, that simply ignore the parameters in making routing decisions, have even worse performance. Three alternative strategies are therefore examined: threshold, discriminatory, and adaptive. Instead of just optimizing an incoming transaction's response time, the first two strategies pursue a strategy that is somewhat more oriented towards global optimization. This is achieved by being more restrictive on either the condition or the candidate for balancing the load. The third strategy, while trying to minimize the response time of individual incoming transactions, employes a feedback process to adaptively adjust future response time estimates. It monitors the discrepancy between the actual and estimated response times and introduces a correction factor based on regression analysis. All three strategies are shown to be robust with respect to the accuracy of workload and system parameters used in the response time estimation.

关键词： ALGORITHM DESIGN MANAGEMENT PERFORMANCE distributed database LOAD BALANCING PERFORMANCE ANALYSIS TRANSACTION ROUTING

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