Virtual schemas and bases

Santos, Cassio Souza dos; Abiteboul, Serge; Delobel, Claude

doi:10.1007/3-540-57818-8_43

Cited by 52 publications

(16 citation statements)

References 15 publications

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“…Several object view mechanisms have been proposed since the early 90s [4,1,14,16,7]. In general, the main problems with these views are [16] (i) expressive power (restrictions on queries defining views), (ii) reusability and modeling accuracy (insertion of the views into the generalization hierarchy), and (iii) consistency (stability in OlD generation).…”

Section: Resultsmentioning

confidence: 99%

“…Problems (i) and (ii) are somewhat related. For example, using the view mechanism in [14], if the user wants the view class to be linked to the generalization hierarchy, the query that generates the view class has to be restricted. In addition, the problem (ii) raises a typing problem (how is the type of the virtual class related to the type hierarchy?)…”

Section: Resultsmentioning

confidence: 99%

“…O2 Views [14], makes the distinction between virtual classes that select through queries existing objects in the database and imaginary classes for which the selected objects are restructured and turned into objects. Virtual classes are connected to the generalization hierarchy by a maybe relationship whereas imaginary classes are not.…”

Section: Multiviewmentioning

confidence: 99%

“…Despite several research efforts in the object-oriented community [4,1,14,16], the objective of a view mechanism, as defined for the relational model, has not yet been achieved. The problem is more complex and may be too general in the object-oriented environment.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Defining Views in an Image Database System

et al. 1999

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A view mechanism can help handle the complex semantics in emerging application areas such as image databases. This paper presents the view mechanism we defuted for the DISIMA image database system. Since DISIMA is being developed on top of an object-oriented database system, we first propose a powerful object-oriented view mechanism based on the separation between types (interface functions) and classes that manage objects of the same type. The image view mechanism uses our object-oriented view mechanism to allow us to give different semantics to the same image. The solution is based on the distinction between physical salient objects which are interesting objects in an image and logical salient objects which are the meanings of these objects.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Multiviewmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Defining Views in an Image Database System

et al. 1999

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“…However, the issues involved have received considerable interest within the database community for over a decade [1,2,10,19]. In particular, the problem of data integration in Heterogeneous Database Systems (HDBS) has a marked similarity to the problem discussed in this paper.…”

Section: Towards Virtual Case Basesmentioning

confidence: 98%

Separating the cases from the data: Towards more flexible case-based reasoning

Brown

Watson

Filer

1995

Case-Based Reasoning Research and Development

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Abstract. The number of successful, small-scale and purpose-built applications of CBR is growing rapidly. However, CBR has so far not been widely used as a methodology for reusing the large-scale data repositories typically maintained by a corporation. To facilitate this, cases must no longer be considered as concretely represented at the data level, but as virtual views of the underlying data. This paper argues that the basic requirement to support virtual cases are mapping functions between different data representations. It is argued that the use of mapping functions can increase flexibility in a number of ways. Multiple CBR applications can exploit a single database. Similarly, a single case representation can span multiple databases. Support for communication between different CBR applications as well as the evolution of case representation within a single application are also catered for by the same methodology. The paper provides reference to related work on database systems, with respect to the issues of mapping function implementation and management.

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Distributed data integration by object‐oriented mediator servers

Risch

Josifovski

2001

Concurrency and Computation

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SUMMARYIntegration of data from autonomous, distributed and heterogeneous data sources poses several technical challenges. This paper overviews the data integration system AMOS II based on the wrapper-mediator approach. AMOS II consists of: (i) a mediator database engine that can process and execute queries over data stored locally and in several external data sources, and (ii) object-oriented (OO) multi-database views for reconciliation of data and schema heterogeneities among sources with various capabilities. The data stored in different types of data sources is translated and integrated using OO mediation primitives, providing the user with a consistent view of the data in all the sources. Through its multi-database facilities many distributed AMOS II systems can interoperate in a federation. Since most data reside in the data sources, and to achieve high performance, the core of the system is a main-memory DBMS having a storage manager, query optimizer, transactions, client-server interface, disk backup, etc. The AMOS II data manager is optimized for main-memory access and is extensible so that new data types and query operators can be added or implemented in some external programming language. The extensibility is essential for providing seamless access to a variety of data sources.

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Virtual schemas and bases

Cited by 52 publications

References 15 publications

Defining Views in an Image Database System

Defining Views in an Image Database System

Separating the cases from the data: Towards more flexible case-based reasoning

Distributed data integration by object‐oriented mediator servers

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