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9th International Conference on Information and Knowledge Management (CIKM 2000)

作者： Pedersen, Torben Bach Shoshani, Arie Gu, Junmin Jensen, Christian S. Department of Computer Science Aalborg University Denmark Lawrence Berkeley National Laboratory United States

ISBN: (纸本)9781581133202

On-Line Analytical Processing (OLAP) systems based on a multidimensional view of data have found widespread use in business applications and are being used increasingly in non-standard applications. These systems provide good performance and ease-of-use. However, the complex structures and relationships inherent in data in non-standard applications are not accommodated well by OLAP systems. In contrast, object database systems are built to handle such complexity, but do not support OLAP-type querying well. This paper presents the concepts and techniques underlying a flexible, "multi-model" federated system that enables OLAP users to exploit simultaneously the features of OLAP and object database systems. The system allows data to be handled using the most appropriate data model and technology: OLAP systems for multidimensional data and object database systems for more complex, general data. Additionally, physical data integration can be avoided. As a vehicle for demonstrating the capabilities of the system, a prototypical OLAP language is defined and extended to naturally support queries that involve data in object databases. The language permits selection criteria that reference object data, queries that return combinations of OLAP and object data, and queries that group multidimensional data according to object data. The system is designed to be aggregation-safe, in the sense that it exploits the aggregation semantics of the data to prevent incorrect or meaningless query results. A prototype implementation of the system is reported. © ACM 2000.

关键词： object-oriented databases

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A Meta Model and an Infrastructure for the Non-Transparent Replication of object databases 00

A Meta Model and an Infrastructure for the Non-Transparent R...

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9th International Conference on Information and Knowledge Management (CIKM 2000)

作者： Dreyer, Werner Dittrich, Klaus R. Microsoft Corp. United States Database Technology Research Group Department of Information Technology University of Zurich Switzerland

ISBN: (纸本)9781581133202

The distribution of data within or between organizations is crucial for many applications. Such a distribution may be transparent, as it is embodied in distributed database systems to increase their performance, reliability and availability. Other systems either do not require transparent data distribution or even explicitly need their own copies of the data. Examples are data warehouses which collect base data from different transaction processing systems, or financial data distribution systems in banking where data are bought from external providers and distributed to different working groups. Such systems need non-transparent, partial and selective replication of databases. If object databases are used, appropriate replication systems have to cope with the additional complexity of object models. TodayÕs replication systems do not meet these requirements. Consequently, we introduce a meta model that specifies the abstract functionality which is needed for the non-transparent, partial and selective replication of object databases. This meta model allows incorporation of its replication concepts in a variety of object models. In addition, we present the design of a replication infrastructure, based on the meta model, which serves as the foundation for concrete realizations of object replication systems. The development of a replication system for a time series database management system proved the viability of the proposed solution. © ACM 2000.

关键词： object-oriented databases

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OLAP++: Powerful and easy-to-use federations of olap and object databases

OLAP++: Powerful and easy-to-use federations of olap and obj...

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26th International Conference on Very Large Data Bases, VLDB 2000

作者： Gu, Junmin Pedersen, Torben Bach Shoshani, Arie Lawrence Berkeley National Laboratory Berkeley CA 94720 United States Department of Computer Science Aalborg University 9220 Aalborg Denmark

We describe the OLAP++ system for federating OLAP and object databases. The system allows users to easily pose OLAP queries that reference external object databases. This enables very flexible and fast integration of ... 详细信息

ISBN: (纸本)1558607153

关键词： object-oriented databases

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On-line Reorganization in object databases 00

On-line Reorganization in Object Databases

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2000 ACM SIGMOD International Conference on Management of Data, SIGMOD 2000

作者： Lakhamraju, Mohana K. Rastogi, Rajeev Seshadri, S. Sudarshan, S. University of California BerkeleyCA United States Bell Labs Murray HillNJ United States Indian Institute of Technology Bombay India

ISBN: (纸本)9781581132175

Reorganization of objects in an object databases is an important component of several operations like compaction, clustering, and schema evolution. The high availability requirements (24 X 7 operation) of certain application domains requires reorganization to be performed on-line with minimal intereference to concurrently executing transactions. In this paper, we address the problem of on-line reorganization in object databases, where a set of objects have to be migrated from one location to another. Specifically, we consider the case where objects in the database may contain physical references to other objects. Relocating an object in this case involves finding the set of objects (parents) that refer to it, and modifying the references in each parent. We propose an algorithm called the Incremental Reorganization Algorithm (IRA) that achieves the above task with minimal interference to concurrently executing transactions. The IRA algorithm holds locks on at most two distinct objects at any point of time. We have implemented IRA on Brahma, a storage manager developed at IIT Bombay, and conducted an extensive performance study. Our experiments reveal that IRA makes on-line reorganization feasible, with very little impact on the response times of concurrently executing transactions and on overall system throughput. We also describe how the IRA algorithm can handle system failures. © ACM 2000

关键词： object-oriented databases

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Building an active material requirements planning system

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INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2000年第2期38卷 241-252页

作者： Du, TCT Wolfe, PM Arizona State Univ Dept Ind & Management Syst Engn Tempe AZ 85287 USA Chung Yuan Christian Univ Dept Ind Engn Chungli 32023 Taiwan

A material requirements planning (MRP) system is usually implemented with several constraints, such as replenishment of inventories on a period-by-period bases, which obstruct its dynamic performance. This research proposes an active, bucketless, and real-time MRP system. The active MRP system utilizes hybrid architecture that includes an object-oriented database, fuzzy logic controllers, and neural networks. The object-oriented database, which maintains static data relationships, provides superior capabilities in reusability, complex structure operations, and potential integration. The complementary combination of fuzzy logic controllers and neural networks provides a model-free, human-like decision system. Adding triggers and assertions forms an active MRP model.

关键词： MATERIAL requirements planning INVENTORIES object-oriented databases NEURAL networks (Computer science) databases DECISION support systems FUZZY systems

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Dynamic SEOF: An adaptable object prefetch policy for object-oriented database systems

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COMPUTER JOURNAL 2000年第6期43卷 524-537页

作者： Ahn, JH Kim, HJ Seoul Natl Univ Dept Comp Engn OOPSLA Lab Seoul 151742 South Korea

When accessing objects in an object-oriented database, performance can be greatly improved by prefetching objects efficiently. In this paper we present a new object prefetch policy, dynamic selective eager object fetch (SEOF), which prefetches objects only from selected candidate pages without using any high-level object semantics. Our policy considers both correlations and frequencies of fetching objects when selecting prefetch candidates. Unlike existing prefetch policies, dynamic SEOF utilizes the memory and the swap space of clients efficiently without resource exhaustion. Furthermore, the proposed policy has good adaptability to both the effectiveness of clustering and database size. It also adjusts the degree of prefetching dynamically according to the working environment. We show the performance of the proposed policy through experiments over various multi-client system configurations.

关键词： Database systems access object object-oriented databases work environment Working Conditions prefetching Policies

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Updates and object-generating views in ODBS

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DATA & KNOWLEDGE ENGINEERING 2000年第2期34卷 125-163页

作者： Bellahsene, Z Univ Montpellier 2 CNRS UMR 55060 LIRMM F-34392 Montpellier 5 France

In object-oriented database systems, a view mechanism can extend the object paradigm by adapting object structure and object behavior to the needs of the different applications or users. In this paper we consider views with object-generating semantics which is an important construct in database environment and mediator systems (Y. Papakonstantinou, S. Abiteboul, H. Garcia-Molina, object Fusion in Mediator Systems, in: Proceedings of the International Conference on Very Large databases, New York, July 1998). We reexamine the problem of updating views according to the aspects of object-orientation, namely: object identity, inheritance and aggregation path. Furthermore, rye propose a taxonomy of virtual classes in order to define the update semantics with respect to the virtual class semantics. We present also a cost model for our update algorithms to quantify the impact of our materialization method upon updates propagation times. (C) 2000 Elsevier Science B.V. All rights reserved.

关键词： object-oriented databases object identity view updating materialized views object-generated views

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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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Optimizing object queries using an effective calculus

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ACM TRANSACTIONS ON DATABASE SYSTEMS 2000年第4期25卷 457-516页

作者： Fegaras, L Maier, D Univ Texas Dept Comp Sci & Engn Arlington TX 76019 USA Oregon Grad Inst Sci & Technol Dept Comp Sci & Engn Beaverton OR 97006 USA

object-oriented databases (OODBs) provide powerful data abstractions and modeling facilities, but they generally lack a suitable framework for query processing and optimization. The development of an effective query optimizer is one of the key factors for OODB systems to successfully compete with relational systems, as well as to meet the performance requirements of many nontraditional applications. We propose an effective framework with a solid theoretical basis for optimizing OODB query languages. Our calculus, called the monoid comprehension calculus, captures most features of ODMG OQL, and is a good basis for expressing various optimization algorithms concisely. This article concentrates on query unnesting (also known as query decorrelation), an optimization that, even though it improves performance considerably, is not treated properly (if at all) by most OODB systems. Our framework generalizes many unnesting techniques proposed recently in the literature, and is capable of removing any form of query nesting using a very simple and efficient algorithm. The simplicity of our method is due to the use of the monoid comprehension calculus as an intermediate form for OODB queries. The monoid comprehension calculus treats operations over multiple collection types, aggregates, and quantifiers in a similar way, resulting in a uniform method of unnesting queries, regardless of their type of nesting.

关键词： experimentation performance object-oriented databases nested relations query decorrelation query optimization

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