The use of distributed databases in e-learning systems

AbstractE-learning: The modern technologies in education and research aims to build a society based on knowledge. In this paper we will describe the advantages of e-learning education and the importance of data allocation in the process of designing a distributed database system. In addition, we are going to analyze the available strategies for optimizing the query execution in a distributed environment, in order to obtain the smallest system response time. The purpose of this paper is to present the advantages offered by the use of distributed databases in the education field by universities with geographically distributed locations

Efficient Database Distribution Using Local Search Algorithm

A problem in railway database is identied. Focus of the problem is to reduce the average response time for all the read and write queries to the railway database. One way of doing this is by opening more than one database servers and distributing the database across these servers to improve the performance. In this work we are proposing an ecient distribution of the database across these servers considering read and write request frequencies at all locations. The problem of database distribution across dierent locations is mapped to the well studied problem called Uncapacitated Facility Location(UFL) problem. Various techniques such as greedy approach, LP rounding technique, primal-dual technique and local search have been proposed to tackle this problem. Of those, we are using local search technique in this work. In particular, poly- nomial version of the local search approximation algorithm is used to solve the railway database problem. Distributed database is implemented using postgresql database server and jboss appli- cation server is used to manage the global transaction. On this architecture, database is distributed using the local optimal solution obtained by local search algorithm and it is compared with other solutions in terms of the average response time for the read and write requests

Data replication in distributed environments

Distributed system model best suits on the organizational structure of companies that, because of their business needs, are geographically distributed. For the organizations that are expanding globally, the data exchange between multiple databases and applications has become more important. In distributed environments we are facing new problems that are not relevant in centralized environments, such as data fragmentation and replication. Designing a distributed database system also involves the decisions about placing the information on different sites in a computer network. The problem of data fragments allocation on different sites is closely related to data replication in distributed databases. In this paper we will concentrate on data allocation problem, revealing the data allocation importance in the process of the distributed database design in correlation with data fragmentation. In addition, we will analyze the available strategies and methods of data allocation.replication, strategies, methods of data allocation.

Distributed databases

Mòdul 3 del llibre Database Architecture. UOC, 20122022/202

Composite information systems : resolving semantic heterogeneities

"March 1991."Includes bibliographical references (p. 14-16).Michael Siegel, Stuart Madnick, Amar Gupta

Consideration of interdependencies in the relational database system, and, A proposal and evaluation of an expert system for the relational database structure

This thesis addresses the issue of interdependencies in Distributed and non-Distributed Relational Database Management Systems and proposes a design and development of an Expert System to manage and enhance the current available Database Structures; In the first part, we study, compare and evaluate the interdependencies found in the operating environment relevant to the Distributed Relational structure. Hardware and software configurations are grouped and compared in an attempt to understand the interdependencies of the system so that an optimal configuration may be obtained; In the second part, we designed and developed an Expert System configuration with ease of use and functionality as foremost concerns. The system reuses the transient tables used to service queries to achieve a performance improvement without explicit user knowledge. Basic fragmentation principles are also used to aid in performance by implicitly restructuring the tables within a database to balance access time. (Abstract shortened with permission of author.)

Binary vote assignment on grid quorum replication technique with association rule

One of the biggest challenges that data grids users have to face today relates to the improvement of the data management. Organizations need to provide current data to users who may be geographically remote and to handle a volume of requests of data distributed around multiple sites in distributed environment. Therefore, the storage, availability, and consistency are important issues to be addressed to allow efficient and safe data access from many different sites. One way to effectively cope with these challenges is to rely on the replication technique. Replication is a useful technique for distributed database systems. Through this technique, a data can be accessed from multiple locations. Thus, replication increases data availability and accessibility to users. When one site fails, user still can access the same data at another site. Techniques such as Read-One-Write-All (ROWA), Hierarchical Replication Scheme (HRS) and Branch Replication Scheme (BRS) are the popular techniques being used for replication and data management. However, these techniques have its weaknesses in terms of communication costs that is the total replication servers needed to replicate the data. Furthermore, these techniques also do not consider the correlation between data during the fragmentation process. The knowledge about data correlation can be extracted from historical data using techniques of the data mining field. Without proper strategies, replication increases job execution time. In this research, the some-data-to-some-sites scheme called Binary Vote Assignment on Grid Quorum with Association (BV AGQAR) is proposed to manage replication for meaningful fragmented data in distributed database environment with low communication cost and processing time for a transaction. The main feature of BV AGQ-AR is that the technique integrates replication and data mining technique allowing meaningful extraction of knowledge from large data sets. Performance of the BVAGQ-AR technique comprised the following steps. First step is mining the data by using Apriori algorithm from Association Rules. It is used to discover the correlation between data. For the second step, the database is fragmented based on the data mining analysis results. This technique is executed to make sure data replication can be effectively done while saving cost. Then, the databases that are resulted after the fragmentation process are allocated at their assigned sites. Finally, after allocation process, each site has a database file and ready for any transaction and replication process. Finally, the result of the experiments shows that BV AGQ-AR can preserve the data consistency with the lowest communication cost and processing time for a transaction as compared to BCSA, PRA, ROW A, HRS and BRS