78,904 research outputs found

    Schema architecture and their relationships to transaction processing in distributed database systems

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    We discuss the different types of schema architectures which could be supported by distributed database systems, making a clear distinction between logical, physical, and federated distribution. We elaborate on the additional mapping information required in architecture based on logical distribution in order to support retrieval as well as update operations. We illustrate the problems in schema integration and data integration in multidatabase systems and discuss their impact on query processing. Finally, we discuss different issues relevant to the cooperation (or noncooperation) of local database systems in a heterogeneous multidatabase system and their relationship to the schema architecture and transaction processing

    Developing Translation Rules for Converting Relational to Object Oriented Database Conceptual Schema

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    A multidatabase is a confederation of pre-existing distributed, heterogeneous, and autonomous database system. Obviously, the integration process is essential in the effort of forming a distributed, heterogeneous database system. This process generally consists of two main phases, which are conceptual schema translation phase followed by the integration phase. This paper presents a translation approach to convert relational database schema to object-oriented database schema. The translation approach consists of a set of translation rules, which is based on inclusion dependencies, key attributes and types of attributes. A database schema translation tool prototype, called RETOO (RElational-ToObject- Qriented) is then developed based on the proposed translation approach. RETOO receives a relational database schema as input data and generates an object-oriented database schema as the output. The translation approach is not only able to maintain the semantics of the relational database schema, but also enhance the semantics of the translated object-oriented schema via objectoriented data modeling concepts

    The schema coercion problem

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    Journal ArticleOver the past decade, the ability to incorporate data from a wide variety of sources has become increasingly important to database users. To meet this need, significant effort has been expended in automatic database schema manipulation. However, to date this effort has focused on two aspects of this problem: schema integration and schema evolution. Schema integration results in a unified view of several databases, while schema evolution enhances an existing database design to represent additional information. This work defines and addresses a third problem, schema coercion, which defines a mapping from one database to another. This paper presents an overview of the problems associated with schema coercion and how they correspond to the problems encountered by schema integration and schema evolution. In addition, our approach to this problem is outlined. The feasibility of this approach is demonstrated by a tool which reduces the human interaction required at all steps in the integration process. The database schemata are automatically read and converted into corresponding ER representations. Then, a correspondence identification heuristic is used to identify similar concepts, and create mappings between them. Finally, a program is generated to perform the data transfer. This tool has successfully been used to coerce the Haemophilus and Methanococcus genomes from the Genbank ASN.l database to the Utah Center for Human Genome Research database. Our comprehensive approach to addressing the schema coercion problem has proven extremely valuable in reducing the interaction required to define coercions, particularly when the heuristics are unsuccessful

    Negotiation in Database Schema Integration

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    Databases are playing an increasingly important role in organizations. Timely, accurate access to information has become a critical component of gaining competitive advantage. Data availability is commonly perceived as a critical success factor for an organizationÕs long-term survival, and day-to-day operations can be crippled by failure of the database system to satisfy user requirements. However, a number of emerging issues complicate organizationsÕ ability to provide comprehensive and reliable access to disparate information resources. Further, data accessibility is often compromised due to the typically high cost associated with addressing these issues in practice. Examples of such issues which have emerged in the past decade include the proliferation and investment in autonomous databases within organizations, heterogeneity among data models and database management systems employed, the increasingly important role of distributed systems, and the increasing complexity and knowledge-intensive nature of integrating database schemas. All these factors contribute to the increasing importance of developing feasible options for providing interoperability among existing databases, and therefore, of pursuing research in the area of database schema integration. Indeed, this research focuses specifically on knowledge requirement problems involved in integrating the schema of existing databases in order to provide interoperability and transparent access to disparate information resources without the investment involved in complete systems redesig

    Translating Relational Conceptual Schema to Object-Oriented Schema

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    A multidatabase is a confederation of preexisting distributed, heterogeneous, and autonomous database system. The integration process is essential in the effort of forming a distributed, heterogeneous database system. This process generally consists of two main phases, which are conceptual schema translation phase and followed by the integration phase. In our research, we have proposed an alternative translation approach to convert relational database schema to object--oriented database schema. The translation approach consists of a set of translation rules, which are based on inclusion dependencies, key attributes and types of attributes. A database schema translation tool prototype, called RETOO (Relational-to-Object-Oriented) is then developed based on the proposed translation approach. RETOO receives a relational database schema as input data and generate an object-oriented database schema as the output data.RETOO operates semi-automatically, especially in the process of identifying operations for each class. This is because relational data model does not provide the behavioural information of every entity. The translation approach and RETOO database translation tool prototype are not only able to maintain the semantics of the relational database schema, but also enhance the semantics of the translated object-oriented schema via object-oriented data modelling concepts

    Schema Management for Data Integration: A Short Survey

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    Schema management is a basic problem in many database application domains such as data integration systems. Users need to access and manipulate data from several databases. In this context, in order to integrate data from distributed heterogeneous database sources, data integration systems demand the resolution of several issues that arise in managing schemas. In this paper, we present a brief survey of the problem of schema matching which is used for solving problems of schema integration processing. Moreover, we propose a technique for integrating and querying distributed heterogeneous XML schemas.

    A Rule-Based Approach to Analyzing Database Schema Objects with Datalog

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    Database schema elements such as tables, views, triggers and functions are typically defined with many interrelationships. In order to support database users in understanding a given schema, a rule-based approach for analyzing the respective dependencies is proposed using Datalog expressions. We show that many interesting properties of schema elements can be systematically determined this way. The expressiveness of the proposed analysis is exemplarily shown with the problem of computing induced functional dependencies for derived relations. The propagation of functional dependencies plays an important role in data integration and query optimization but represents an undecidable problem in general. And yet, our rule-based analysis covers all relational operators as well as linear recursive expressions in a systematic way showing the depth of analysis possible by our proposal. The analysis of functional dependencies is well-integrated in a uniform approach to analyzing dependencies between schema elements in general.Comment: Pre-proceedings paper presented at the 27th International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2017), Namur, Belgium, 10-12 October 2017 (arXiv:1708.07854
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