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Design of a new indexing organization for a class-aggregation hierarchy in object-oriented databases

JOURNAL OF INFORMATION SCIENCE AND ENGINEERING 1999年第2期15卷 217-241页

作者： Lee, CI Chang, YI Yang, WP Natl Tainan Teachers Coll Inst Informat Educ Tainan 700 Taiwan Natl Sun Yat Sen Univ Dept Appl Math Kaohsiung 804 Taiwan Natl Chiao Tung Univ Dept Comp & Informat Sci Hsinchu 300 Taiwan

In an object-oriented database, a class consists of a set of attributes, and the values of the attributes are objects that belong to other classes;that is, the definition of a class forms a class-aggregation hierarchy of classes. A branch of such a hierarchy is called a path. Several index organizations have been proposed to support object-oriented query languages, including multiindex, join index, nested index and path index. All the proposed index organizations are helpful only for a query which retrieves the objects of the root class of a given path using a predicate which specifies the value of the attribute at the end of the path. In this paper, we propose a new index organization for evaluating queries, called full index, where an index is allocated for each class and its attribute (or nested attribute) along the path. From the analysis results, we show that a full index can support any type of query along a given path with a lower retrieval cost than all the other index organizations. Moreover, to reduce the high update cost for a long given path, we split the path into several subpaths and allocate a separate index to each subpath. Given a path, the number of subpaths and the index organization of each subpath define an index configuration. Since a low retrieval cost and a low update cost are always a trade-off in index organizations, we also propose cost formulas to determine the index configuration which can provide the best performance for various applications by taking into account various types of queries along a given path and a set of queries with more than one nested predicate along a given path.

关键词： access methods complex objects index selection object-oriented databases query optimization

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Support for modeling relationships in object-oriented databases

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DATA & KNOWLEDGE ENGINEERING 1999年第3期29卷 227-257页

作者： Beraha, S Su, JW Univ Calif Santa Barbara Dept Comp Sci Santa Barbara CA 93106 USA

Modeling real-world applications typically consists of two parts: the representations of entities of interest, and the representations of relationships among the entities. object-oriented data models support the first task. This paper argues through examples that the second modeling task is not well supported in current object-oriented database systems. An extended object-oriented data model that facilitates both modeling tasks is developed. This extension provides support for both the representation of complex relationships among entities and their manipulations (queries, updates). A prototype implemented on the ONTOS database management system is briefly described. (C) 1999 Elsevier Science B.V. All rights reserved.

关键词： data modeling object-oriented databases entity and relationship models nested relationships database design database query languages

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Formal approach for reengineering fuzzy XML in fuzzy object-oriented databases

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APPLIED INTELLIGENCE 2013年第4期38卷 541-552页

作者： Liu, Jian Ma, Z. M. Feng, Xue Northeastern Univ Sch Informat Sci & Engn Shenyang 110004 Peoples R China Shenyang Mil Command Gen Hosp Shenyang Peoples R China

Since semi-structured documents (e.g., XML) could benefit greatly from database support and more specifically from object-oriented (OO) database management systems, we study the methodology of reengineering XML to object-oriented databases when database migration occurs in this paper. In particular, considering the need of processing the imprecise and uncertain information existing in practical applications, we investigate the problem of migrating fuzzy XML to fuzzy object-oriented databases. To find the object-oriented schema that best describes the existing fuzzy XML schema (DTD), we devise a comprehensive approach centering on a set of mapping rules. Such reengineering practices could not only provide a significant consolidation of the interoperability between fuzzy OO and fuzzy XML modeling techniques, but also develop the practical design methodology for fuzzy OO databases.

关键词： object-oriented databases XML Imprecise and uncertain information Mapping

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Consistency management in object-oriented databases

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2001年第11期13卷 955-985页

作者： Oakasha, H Conrad, S Saake, G Univ Munich Inst Informat D-80538 Munich Germany Cairo Univ Fayoum Branch Fac Sci Al Fayyum Egypt Univ Magdeburg Fak Informat D-39016 Magdeburg Germany

The paper presents concepts and ideas underlying an approach for consistency management in object-oriented (OO) databases. In this approach constraints are considered as first class citizens and stored in a meta-database called constraints catalog. When an object is created constraints of this object are retrieved from the constraints catalog and relationships between these constraints and the object are established. The structure of constraints has several features that enhance consistency management in OO database management systems which do not exist in conventional approaches in a satisfactory way. This includes: monitoring object consistency at different levels of update granularity, integrity independence, and efficiency of constraints maintenance;controlling inconsistent objects;enabling and disabling constraints, globally to all objects or locally to individual objects;and declaring constraints on individual objects. All these features are provided by means of basic notations of OO data models. Copyright (C) 2001 John Wiley & Sons, Ltd.

关键词： object-oriented databases constraint management constraint maintenance database integrity integrity constraints

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An evaluation of vertical class partitioning for query processing in object-oriented databases

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IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 2002年第5期14卷 1095-1118页

作者： Fung, CW Karlapalem, K Li, Q Vocat Training Council Hong Kong Inst Vocat Educ Tuen Mun Dept Informat & Commun Technol Tuen Mun Hong Kong Peoples R China Int Inst Informat Technol Hyderabad 500019 Andhra Pradesh India City Univ Hong Kong Dept Comp Engn & Informat Technol Kowloon Hong Kong Peoples R China

Vertical partitioning is a design technique for reducing the number of disk accesses to execute a given set of queries by minimizing the number of irrelevant instance variables accessed. This is accomplished by grouping the frequently accessed instance variables as vertical class fragments. The complexity of object-oriented database models due to subclass hierarchy and class composition hierarchy complicates the definition and representation of vertical partitioning of the classes, which makes the problem of vertical partitioning in OODBs very challenging. In this paper, we develop a comprehensive analytical cost model for processing of queries on vertically partitioned OODB classes. A set of analytical evaluation results is presented to show the effect of vertical partitioning, and to study the trade-off between the projection ratio versus selectivity factor vis-a-vis sequential versus index access. Furthermore, an empirical experimental prototype supporting vertical class partitioning has been implemented on a commercial OODB tool kit to validate our analytical cost model.

关键词： class partitioning vertical partitioning query processing object-oriented databases analytical cost model

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On modeling cost functions for object-oriented databases

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IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 1997年第3期9卷 500-508页

作者： Bertino, E Foscoli, P Dipartimento di Scienze dell'Informazione Università di Milano-Bicocca Milan Italy Universita degli Studi di Milano Milano Lombardia IT

In this paper, we present a set of parameters able to exactly model topologies of object references in object-oriented databases. These parameters are important since they are used to model query execution strategy costs for optimization. The model we present considers also the cases of multivalued attributes and null references. Moreover, a set of derived parameters are introduced and their mathematical derivations are shown. These derived parameters are important, since they allow selectivity of nested predicates to be estimated. Moreover, they are used in estimating storage, access, and update costs for a number of access structures specifically tailored to efficiently support object-oriented queries.

关键词： object-oriented databases complex objects inheritance query languages query processing data structures

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ON USING PROLOG TO IMPLEMENT object-oriented databases

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INFORMATION AND SOFTWARE TECHNOLOGY 1993年第5期35卷 301-311页

作者： PATON, NW LEISHMAN, S EMBURY, SM GRAY, PMD UNIV ABERDEEN KINGS COLLDEPT COMP SCIABERDEEN AB9 2UBSCOTLAND

This Paper outlines the use of Prolog for implementing object-oriented databases (OODBs), to indicate both the benefits and costs associated with Prolog as an implementation platform. The different roles which Prolog can play in the implementation of an OODB are illustrated hy reference to example systems which, although they use Prolog as an implementation language, have significantly different architectures. These architectures are compared and assessed, both in terms of the functionality provided to users, and performance.

关键词： PROLOG object-oriented databases DATABASE PROGRAMMING

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ALGORITHMS FOR ASYNCHRONOUS PARALLEL-PROCESSING OF object-oriented databases

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IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 1995年第3期7卷 487-504页

作者： THAKORE, AK SU, SYW LAM, HX UNIV FLORIDA DEPT ELECT ENGNDEPT COMP & INFORMAT SCICTR DATABASE SYST RES & DEVGAINESVILLEFL 32611

Management of large quantities of complex data is essential in many advanced application areas object-oriented (OO) database management system have been developed to effectively model and process the complex domain knowledge. They have been shown to outperform sam existing relational systems. The existing implementations of OO database management system attempt to improve the efficiency of OO queries by explicitly capturing the relationships among objects. However, the execution of complex queries involving the retrieval of objects from many classes and relationships among them causes the existing system to operate inefficiently. In this paper, we present parallel algorithms for the processing of queries against a large OO database The algorithms are based on a closed model of query processing using pattern-based access instead of the conventional value-based access. During processing, the algorithms avoid the execution of time-consuming join operations by making use of the explicitly stared object associations. Generation of large quantities of temporary data is avoided by marking objects using their identifiers and by employing a two-phase query processing strategy, A query is processed by concurrent multiple waves, thereby improving parallelism and avoiding the complexities introduced in their sequential implementation. The correctness and the performance of the parallel algorithms have been tested and analyzed by running parallel programs on a 32-node Transputer based parallel machine designed and developed at the IBM Research Center at Yorktown Heights, New York Benchmark queries of different semantic complexities are generated, and their performance is analyzed for various data and query parameters.

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

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Views as first-class citizens in object-oriented databases

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VLDB JOURNAL 2005年第2期14卷 155-169页

作者： Alhajj, R Polat, F Yilmaz, C Univ Calgary Dept Comp Sci Calgary AB T2N 1N4 Canada Middle E Tech Univ Dept Comp Engn TR-06531 Ankara Turkey

Extensibility and dynamic schema evolution are among the attractive features that lead to the wide acceptance of the object-oriented paradigm. Not knowing all class hierarchy details should not prevent a user from introducing new classes when necessary. Naive or professional users may define new classes either by using class definition constructs or as views. However, improper placement of such classes leads to a flat hierarchy with many things duplicated. To overcome this problem, we automated the process in order to help the user find the most appropriate position with respect to her class in the hierarchy regardless of her knowledge of the hierarchy. The system must be responsible for the proper placement of new classes because only the system has complete knowledge of the details of the class hierarchy, especially in a dynamic environment where changes are very frequent. In other published work, we proved that to define a view it is enough to have the set of objects that qualify to be in a view in addition to having message expressions (possible paths) that lead to desired values within those objects. Here, we go further to map a view that is intended to be persistent into a class. Then we investigate the proper position of that class in the hierarchy. To achieve this, we consider current characteristics of a new class in order to derive its relationship with other existing classes in the hierarchy. Another advantage of the presented model is that views that generate new objects are still updatable simply because we based the creation of new objects on existing identities. In other words, an object participates inside view objects by its identity regardless of which particular values from that object are of interest to the view. Values are reachable via message expressions, not violating encapsulation. This way, actual values are present in only one place and can be updated.

关键词： class hierarchy object-oriented databases reusability schema evolution views

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Special issue: object-oriented databases

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2001年第11期13卷 929-931页

作者： Guerrini, G Merlo, I Ferrari, E Centre for Telematics and Information Technology University of Twente Enschede Netherlands University of Twente 7500 AE Enschede PO Box 217 Netherlands

The First ECOOP Workshop on object-oriented databases was held onJune 15, 1999, in Lisboa, Portugal, in conjunction with theThirteenth European Conference of object-oriented Programming. Thegoal of the workshop was to bring together researchers working in thefield of object-oriented databases. IN particular, the aim of theworkshop was twofold: to discuss the research going on In theobject-oriented database field and to critically evaluateobject-oriented database systems in Terms of their current usage,their successes and limitations, and their potential for newapplications.

关键词： Database systems object oriented programming object-oriented databases CONJUNCTION

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