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Hierarchical query execution in a parallel object-oriented database system

PARALLEL COMPUTING 1996年第7期22卷 1017-1048页

作者： Bassiliades, N Vlahavas, I Department of Informatics Aristotle University of Thessaloniki 54006 Thessaloniki Greece

We present a hierarchical query execution strategy for a parallel object-oriented database (OODB) system. The system, named PRACTIC, is based on a concurrent active class management model and is mapped to an abstract hierarchical multiprocessor architecture. The proposed strategy is studied analytically and by simulation on a transputer-based machine, verifying the theoretical results. Although the analysis suits both main-memory and disk-based database systems, it becomes significant for main-memory systems where the multiprocessor initialization and communication overheads are comparable to the actual workload. The hierarchical query execution strategy is proved much better than the usual flat strategy of parallel database systems, except some clearly identified extreme cases, where flat processing is better. Furthermore, we propose a declustering scheme for space optimization to improve processor utilization and single-class query performance, by having different classes share memory and computation power of neighboring processing elements.

关键词： parallel main-memory database system object-oriented databases multiprocessor architecture parallel query execution analytic performance model simulation

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INFOEXEC - object-oriented SEMANTIC DATABASE IMPLEMENTATION

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INFORMATION AND SOFTWARE TECHNOLOGY 1990年第4期32卷 290-296页

作者： BALFOUR, A BRITTON, C Unisys Europe-Africa Division Charter Place Vine Street Uxbridge UB8 1QE UK

In 1988 Unisys released the InfoExec family of advanced data-management products for its A Series mainframe computer systems. The paper reviews the background to this major development activity and explains why the relational and entity-relational approaches were rejected in favour of an object-oriented/semantic approach. object-oriented/semantic concepts are explained via a simple example and the InfoExec family of software products is briefly described, as is the underlying software structure. The current status and performance of the software is also reviewed.

关键词： database management systems databases object-oriented databases semantic databases

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Applying version management of object-oriented database technology in reactive scheduling

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INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2000年第5期38卷 1183-1200页

作者： Du, TC Chiou, RJ Chung Yuan Christian Univ Dept Ind Engn Chungli 32023 Taiwan

The focal points of reactive scheduling are to resolve the impact of emergent and unexpected situations under a time constraint. This study proposes a reactive scheduling architecture based on version management technology of object-oriented database technology. In this architecture, three independent workspaces are used to generate schedule plans while five function managers interact with one another to support version management functions. This study will demonstrate the different types of strategies for reactive scheduling by considering two types of unexpected events: machine breakdown and lack of materials.

关键词： object-oriented databases PRODUCTION scheduling BREAKDOWNS (Machinery) DOWNTIME (Systems) MATERIALS management INDUSTRIAL management PRODUCTION management (Manufacturing)

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object query optimization through detecting independent subqueries

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INFORMATION SYSTEMS 2000年第8期25卷 467-490页

作者： Plodzien, J Kraken, A Polish Acad Sci Inst Comp Sci PL-00901 Warsaw Poland Polish Japanese Inst Informat Technol Warsaw Poland

The problem of query optimization in object-oriented databases is addressed. We follow the Stack-Based Approach to query languages, which employs the naming-scoping-binding paradigm of programming languages rather than traditional database concepts such as relational/object algebras or calculi. The classical environment stack is a semantic basis for definitions of object query operators, such as selection, projection/navigation, dependent join, and quantifiers. We describe a general object data model and define a formalized OQL-like query language SBQL. Optimization by rewriting concerns queries containing so-called independent subqueries. It consists in detecting them and then factoring outside loops implied by query operators. The idea is based on the formal static analysis of scoping rules and binding names occurring in a query. It is more general than the classical pushing selections/projections before joins. (C) 2001 Elsevier Science Ltd. All rights reserved.

关键词： object-oriented databases query languages stack-based approach query optimization rewriting rules independent subqueries

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Providing assess to a multimedia archive using the World Wide Web and an object relational database management system

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COMPUTING & CONTROL ENGINEERING JOURNAL 1996年第5期7卷 221-226页

作者： Dunlop, A Papiani, M Hey, T Dept. of Electron. & Comput. Sci. Southampton Univ. UK

Reformatting information currently held in databases into Web pages requires significant effort in both creating the pages initially and their subsequent maintenance. We avoid these costs by coupling a Web server indirectly to a multimedia database using additional software we have developed. This software layer translates Web requests for information into SQL queries, and generates Web pages dynamically to display the results to the user. The method we have developed allows users to query the database directly and browse for information.

关键词： World Wide Web costs multimedia database query processing information reformatting Internet Information services and centres SQL object-relational database relational databases maintenance Multimedia object-oriented databases object-oriented databases Web server information browsing multimedia archive access Web pages Relational databases SQL queries multimedia computing

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Opportunistic prioritised clustering framework for improving OODBMS performance

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JOURNAL OF SYSTEMS AND SOFTWARE 2007年第3期80卷 371-387页

作者： He, Zhen Lai, Richard Marquez, Alonso Blackburn, Stephen La Trobe Univ Dept Comp Sci & Comp Engn Bundoora Vic 3086 Australia Australian Natl Univ Dept Comp Sci Canberra ACT 0200 Australia

In object oriented database management systems, clustering has proven to be one of the most effective performance enhancement techniques. Existing clustering algorithms are mainly static, that is re-clustering the object base when the database is off-line. However, this type of re-clustering cannot be used when 24-h database access is required. In such situations dynamic clustering is necessary, since it can re-cluster the object base while the database is in operation. We find that most existing dynamic clustering algorithms do not address the following important points: the use of opportunism to impose the smallest I/O footprint for re-organisation;the re-use of prior research on static clustering algorithms;and the prioritisation of re-clustering so that the worst clustered pages are re-clustered first. Our main achievement in this paper is to create the Opportunistic Prioritised Clustering Framework (OPCF). The framework allows any static clustering algorithm to be made dynamic. Most importantly it allows the created algorithm to have the properties of I/O opportunism and clustering prioritisation which are missing in most existing dynamic clustering algorithms. We have used OPCF to make the static clustering algorithms "Graph Partitioning" and "Probability Ranking Principle" into dynamic algorithms. In our simulation study we found these algorithms outperformed two existing highly competitive dynamic algorithms in a variety of situations. (C) 2006 Elsevier Inc. All rights reserved.

关键词： object-oriented databases clustering caching performance optimization

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CDOL: A comprehensive declarative object language

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DATA & KNOWLEDGE ENGINEERING 1997年第1期22卷 67-111页

作者： Urban, SD Karadimce, AP Dietrich, SW BenAbdellatif, T Chan, HWR Department of Computer Science and Engineering Arizona State University Tempe AZ 85287-5406 USA

In this paper we present a rule-based database language known as CDOL (Comprehensive, Declarative object Language) that is an integration of deductive, object-oriented and active database technology. CDOL provides sublanguages for the expression of derived data, constraints, updates and active rules. The rule-based query language of CDOL provides an expressive approach to extend the stored database with derived attributes and classes. The constraint sublanguage allows explicit declarative specification of integrity constraints as a basis for database consistency. The update sublanguage of CDOL enables ad-hoc declarative update requests, where updates are encapsulated in the methods associated with class definitions, thus conforming to traditional object-oriented design concepts. The active rule sublanguage provides active, user-transparent agents that support reactive behavior within CDOL applications. In particular, active rules can be used to supplement declarative updates to maintain database consistency with respect to the set of integrity constraints. Active rules in general are used to monitor the occurrence of specific events and to serve as alerters and triggers within a CDOL application. This paper presents the rule-based query language of CDOL and illustrates the manner in which the constraint, update and active rule sublanguages build on this declarative framework. The use of methods and transactions are also addressed, together with a discussion of the operational semantics of active rule processing.

关键词： object-oriented databases active rules deductive rules derived data constraints updates rule-based query language

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ROL: A deductive object base language

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INFORMATION SYSTEMS 1996年第5期21卷 431-457页

作者： Liu, MC Department of Computer Science University of Regina Regina Saskatchewan Canada

This paper presents a novel deductive object-oriented database language, called ROL (Rule-based object Language), which is being developed at the University of Regina. ROL effectively integrates important features of object-oriented databases and deductive databases into a uniform framework. It supports object identity, complex objects, classes, class hierarchy, multiple inheritance with overriding, and schema. It also supports structured values such as functor objects and sets, treats them as first class citizens, and provides powerful mechanisms for representing both partial and complete information on sets. It is an extension of pure valued-oriented deductive languages such as Datalog and LDL (without grouping) and subsumes them as special cases. Another novelty is the introduction of a new ordering which can capture the intended semantics of nested sets. The ROL language is given a logical semantics based on this new ordering that accounts in a clean and declarative fashion for all of its object-oriented and value-oriented features as well as the usage of schema in a deductive framework. Copyright (C) 1996 Elsevier Science Ltd

关键词： deductive object-oriented databases deductive databases object-oriented databases logic programming minimal model semantics fixpoint semantics

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Definition and analysis of index organizations for object-oriented database systems

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INFORMATION SYSTEMS 1998年第2期23卷 65-108页

作者： Bertino, E Catania, B Chiesa, L Univ Milan Dipartimento Sci Informaz Milano Italy SIRTI Milano Italy

The efficient execution of queries in object-oriented databases requires the design of specific indexing techniques, to efficiently deal with predicates against nested attributes or against class inheritance hierarchies. Indexing techniques so far proposed can be classified into three groups: inheritance indexing techniques, whose goal is to support queries along inheritance hierarchies;aggregation indexing techniques, dealing with the efficient evaluation of nested predicates;integrated techniques. The aim of this paper is to analyze two techniques providing an integrated support, the path index and the nested-inherited index, with respect to traditional techniques, such as the multi-index and the inherited multi-index. The analysis is performed assuming that multi-valued attributes, as well as instances with null attribute values, are present in the database. For this purpose, the paper first presents the considered techniques. An extension of the path index, firstly defined in [6], is proposed to deal with multi-valued attributes and instances with null attribute values. Then, an analytical cost model for the extended version of the path index is presented. The cost model is finally used, together with the cost models presented in [2], to compare the various index costs, with respect to storage, retrieval, delete and insert operations. The results show that traditional techniques have better performance with respect to storage, delete and insert costs, whereas integrated techniques have lowest costs for retrieval. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.

关键词： object-oriented databases inheritance aggregation efficient query processing data structures

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PERFORMANCE ANALYSIS OF PARALLEL object-oriented QUERY-PROCESSING ALGORITHMS

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DISTRIBUTED AND PARALLEL databases 1994年第1期2卷 59-100页

作者： THAKORE, AK SU, SYW UNIV FLORIDA DEPT ELECT ENGNDEPT COMP & INFORMAT SCICTR DATABASE SYST RES & DEVGAINESVILLEFL

Advanced application domains such as computer-aided design, computer-aided software engineering, and office automation are characterized by their need to store, retrieve, and manage large quantities of data having complex structures. A number of object-oriented database management systems (OODBMS) are currently available that can effectively capture and process the complex data. The existing implementations of OODBMS outperform relational systems by maintaining and querying cross-references among related objects. However, the existing OODBMS still do not meet the efficiency requirements of advanced applications that require the execution of complex queries involving the retrieval of a large number of data objects and relationships among them. Parallel execution can significantly improve the performance of complex OO queries. In this paper, we analyze the performance of parallel OO query processing algorithms for various benchmark application domains. The application domains are characterized by specific mixes of queries of different semantic complexities. The performance of the application domains has been analyzed for various system and data parameters by running parallel programs on a 32-node transputer based parallel machine developed at the IBM Research Center at Yorktown Heights. The parallel processing algorithms, data routing techniques, and query management and control strategies have been implemented to obtain accurate estimation of controlling and processing overheads. However, generation of large complex databases for the study was impractical. Hence, the data used in the simulation have been parameterized. The parallel OO query processing algorithms analyzed in this study are based on a query graph approach rather than the traditional query tree approach. Using the query graph approach, a query is processed by simultaneously initiating the execution at several object classes, thereby, improving the parallelism. During processing, the algorithms avoid the

关键词： object-oriented databases BENCHMARK APPLICATIONS PARALLEL ALGORITHMS PERFORMANCE EVALUATION QUERY PROCESSING

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