This paper addresses reusability maximization by investigating the proper location of a derived class in the class hierarchy. We categorize derived classes into four groups, depending on whether their superclasses and...
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Mapping information between a global schema and its component schemas is vital for global query processing. In this paper, we continue our previous work on schema integration to propose a mechanism for specifying the ...
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In a transaction-time temporal object database system (ODB) an object update creates a new object version, but the old versions are still accessible. Each object version has an associated timestamp, and this versionin...
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object-oriented databases (OODB) have received considerable attention in recent years. Their performance is a critical factor hindering their current use. Several indexing schemes have been proposed in the literature ...
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object-oriented databases (OODB) have received considerable attention in recent years. Their performance is a critical factor hindering their current use. Several indexing schemes have been proposed in the literature for enhancing OODB performance and they are briefly reviewed here. In this paper a new and uniform indexing scheme is proposed. This scheme is based on a single B-tree and combines both the hierarchical and nested indexing schemes. The uniformity of this scheme enables compact and optimized code for dealing with a large range of queries on the one hand, and flexibility in adding and removing indexed paths on the other hand. The performance of the scheme is discussed and an extensive experimental analysis for the class-hierarchy case is presented. The results show the advantages of the scheme for small range, clustered sets queries. (C) 1997 Elsevier Science Ltd.
This paper briefly describes the new results of the Cave Project. Cave Project is a research initiative aiming to make possible a user-transparent distribution of CAD resources over the World Wide Web. Early results o...
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ISBN:
(纸本)9780769508436
This paper briefly describes the new results of the Cave Project. Cave Project is a research initiative aiming to make possible a user-transparent distribution of CAD resources over the World Wide Web. Early results on developing a web based interface for integrated circuits design tools were presented in the late 1990s. By the year 2000, the research focus has been on evolving the tool-tool integration architecture to provide better design flow modeling using object-oriented design representation.
In this paper, we employ the view model given by Bertino to design a secure multi-level object-oriented database system. The central idea is to provide users with multi-level views derived from a single-level secure o...
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In this paper, we employ the view model given by Bertino to design a secure multi-level object-oriented database system. The central idea is to provide users with multi-level views derived from a single-level secure object-oriented database. The database operations performed on multi-level views are decomposed into a set of operations on single-level objects which can be implemented on any conventional mandatory security kernel. We show that this approach allows us to overcome the difficulties of handling content and context dependent classification, dynamic classification and aggregation and inference problems in multi-level object-oriented databases.
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 co...
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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.
The paper focuses on the indexing on non-primitive (complex) values of attributes in an object management system. A new index structure for indexing on set (multivalued) attributes is proposed. This structure is based...
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ISBN:
(纸本)0818681306
The paper focuses on the indexing on non-primitive (complex) values of attributes in an object management system. A new index structure for indexing on set (multivalued) attributes is proposed. This structure is based an a partial order imposed on the values of the indexed attribute, which are subsets of a set of primitive values. It is shown that the proposed index allows the system to efficiently perform typical set operators that are postulated to be applied in object query languages (is-equal, is-subset, is-superset), without performing any costly operations on lists of object identifiers that would be necessary in traditional index structures. The new index structure called partial-order tree, is described and algorithms performing the set operators are outlined.
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