564,683 research outputs found

    Performance related issues in distributed database systems

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    The key elements of research performed during the year long effort of this project are: Investigate the effects of heterogeneity in distributed real time systems; Study the requirements to TRAC towards building a heterogeneous database system; Study the effects of performance modeling on distributed database performance; and Experiment with an ORACLE based heterogeneous system

    Rigorous Design of Fault-Tolerant Transactions for Replicated Database Systems using Event B

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    System availability is improved by the replication of data objects in a distributed database system. However, during updates, the complexity of keeping replicas identical arises due to failures of sites and race conditions among conflicting transactions. Fault tolerance and reliability are key issues to be addressed in the design and architecture of these systems. Event B is a formal technique which provides a framework for developing mathematical models of distributed systems by rigorous description of the problem, gradually introducing solutions in refinement steps, and verification of solutions by discharge of proof obligations. In this paper, we present a formal development of a distributed system using Event B that ensures atomic commitment of distributed transactions consisting of communicating transaction components at participating sites. This formal approach carries the development of the system from an initial abstract specification of transactional updates on a one copy database to a detailed design containing replicated databases in refinement. Through refinement we verify that the design of the replicated database confirms to the one copy database abstraction

    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

    Security Issues in Distributed Database Management Systems: Challenges and Opportunities

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    Database management systems (DBMS) are essential systems of software technologies for multi-level and multi-angled operations with the utmost security. Currently, its form of distributed database, i.e. DDB, is very popular in communication networks. The current write-up is aimed at investigating important security aspects and issues, exploring some major challenges pertinent to the security of DDB, finding solutions to the same, and eventually talking about some future opportunities through promoting research towards curbing these security-related points. To accomplish these tasks, the author has reviewed some of the latest and most pertinent research articles of the last ten years. It comprises the application of DDBMS, major pertinent issues within its range of investigation, and a conclusion

    Database Systems - Present and Future

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    The database systems have nowadays an increasingly important role in the knowledge-based society, in which computers have penetrated all fields of activity and the Internet tends to develop worldwide. In the current informatics context, the development of the applications with databases is the work of the specialists. Using databases, reach a database from various applications, and also some of related concepts, have become accessible to all categories of IT users. This paper aims to summarize the curricular area regarding the fundamental database systems issues, which are necessary in order to train specialists in economic informatics higher education. The database systems integrate and interfere with several informatics technologies and therefore are more difficult to understand and use. Thus, students should know already a set of minimum, mandatory concepts and their practical implementation: computer systems, programming techniques, programming languages, data structures. The article also presents the actual trends in the evolution of the database systems, in the context of economic informatics.database systems - DBS, database management systems ā€“ DBMS, database ā€“ DB, programming languages, data models, database design, relational database, object-oriented systems, distributed systems, advanced database systems

    A Genetic Programming Approach for Distributed Queries

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    With the emergence of relatively inexpensive and advanced communication technology, Distributed Database Management Systems (DDBMS) have become an integral part of many computer applications. Efficient query processing is one of the most important issues in distributed database systems. In a distributed environment, it is common that queries extract data from different sites. It is important to limit the amount of data transfer across different sites. Semijoin is a way to reduce the cost of expensive joins between various sites. A key issue in query optimization based on semijoin reduction is to find a good sequence of semijoins that reduce the relations referenced in a given query before the joins are performed. This paper proposes a new approach, based on Genetic Programming (GP), to improve the process of database query in Distributed Database Systems. A longer version of this paper is available

    Heterogeneous Distributed Data Base Management Systems

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    This work analyzes the design and implementation issues of Heterogeneous Distributed Data Base Management Systems (HDDBMS). To date, HD-DBMS research projects and implementa tions have been limited. The few such systems which have been constructed provide valuable insight into the nature of problems faced due to heterogeneity. Some of these systems (SIRIUS-DELTA, MULTIBASE, AIDA) , are presented in order to examine their solutions to the problems. The major issues described in the thesis are: the architec ture of the distributed system; query translation; schema mapping; and integration of the schemata within the hetero geneous distributed database, in seeking solutions to these issues, an architecture for a HD-DBMS is proposed
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