Post-graduate theses

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Identifier	uch.csd.msc//1996hamilakis
Title	Κατασκευή Ομοσπονδιακού Σχήματος για ΟΣΒΔ από Τοπικά Σχεσιακά Σχήματα
Alternative Title	Construction of a Federated Schema for a FDBS from Local Relational Schemeta
Creator	Hamilakis, Christodoulos
Contributor	Π. Κωνσταντόπουλος
Abstract	Nowadays, an active topic in the area of databases is Heterogeneous Database Systems (HDBSs). HDBSs consist of databases which differ in terms of management systems, schemas, data types etc. One category of HDBSs are Federated Database Systems (FDBSs) which are federations of cooperative, autonomous and heterogeneous database systems. One of the basic components of the architecture of a FDBS is its federated schema, which usually follows a semantically rich data model. The topic of this thesis is the problem of the construction of a federated schema for a FDBS which consists of local relational databases. Our approach includes the development of a method for translating relational schemas to schemas of a semantic data model, and a method for integrating the translated schemas into a federated schema. The assumptions for the local relational schemas are quite loose, and so the translation method can be applied on a large number of relational schemas compared to other known methods or algorithms. The semantic data model followed by the translated schemas has the characteristics of expressiveness and semantic relativism, that are considered necessary for canonical data models of the FDBSs. The integration method comprises five stages : the preintegration stage, the comparison stage, the conforming stage, the merging stage, and the restructuring stage. Especially for the the conforming stage we developed a set of transforming operators, which are offered to the user/designer of the integrated schema in order to resolve the naming and structural conflicts of the component schemas. As far as the merging stage is concerned we used an already existing algorithm for merging schemas. Finally, we propose the implementation of a tool for the construction of federated schemas for FDBSs from local relational schemas, which is based on the methods of translation and integration that we have developed.
Subject	1) Παράλληλα και Κατανεμημένα Συστήματα, 2) Πληροφοριακά Συστήματα και Τεχνολογία Λογισμικού
Issue date	1996-07-01
Date available	1997-06-2
Collection	School/Department--School of Sciences and Engineering--Department of Computer Science--Post-graduate theses
	Type of Work--Post-graduate theses
Permanent Link	https://elocus.lib.uoc.gr//dlib/d/c/c/metadata-dlib-1996hamilakis.tkl
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