Página 1 dos resultados de 982 itens digitais encontrados em 0.009 segundos

Arquitetura de um sistema para integração de bancos de dados com suporte a replicação utilizando tecnologia de grades computacionais.; A resource monitoring and parallel application cooperative scheduling environment on computing grids.

Brito, Mathias Santos de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Relevância na Pesquisa
46.28%

Integração de bancos de dados heterogêneos utilizando grades computacionais.; Heterogeneous databases integration using grid computing.

Kakugawa, Fernando Ryoji
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Relevância na Pesquisa
56.33%

Compartilhamento de objetos compostos entre bases de dados orientadas a objetos; Sharing composite objects in object-oriented databases

Ferreira, João Eduardo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Relevância na Pesquisa
46.11%

Architecture for peer-to-peer databases with routing queries using ant colony algorithm and semantic support

Valêncio, Carlos Roberto; Costa, Leandro Rincon; Neto, Paulo Scarpelini; Cansian, Adriano Mauro
Tipo: Conferência ou Objeto de Conferência Formato: 263-268
ENG
Relevância na Pesquisa
46.28%
In a peer-to-peer network, the nodes interact with each other by sharing resources, services and information. Many applications have been developed using such networks, being a class of such applications are peer-to-peer databases. The peer-to-peer databases systems allow the sharing of unstructured data, being able to integrate data from several sources, without the need of large investments, because they are used existing repositories. However, the high flexibility and dynamicity of networks the network, as well as the absence of a centralized management of information, becomes complex the process of locating information among various participants in the network. In this context, this paper presents original contributions by a proposed architecture for a routing system that uses the Ant Colony algorithm to optimize the search for desired information supported by ontologies to add semantics to shared data, enabling integration among heterogeneous databases and the while seeking to reduce the message traffic on the network without causing losses in the amount of responses, confirmed by the improve of 22.5% in this amount. © 2011 IEEE.

Evaluating certification protocols in the partial database state machine

Sousa, António Luís Pinto Ferreira de; Moura, Francisco Coelho Soares; Pereira, José, 1973-; Oliveira, Rui Carlos Mendes de; Correia Júnior, Alfrânio Tavares
Fonte: IEEE Computer Society Publicador: IEEE Computer Society
Tipo: Conferência ou Objeto de Conferência
Relevância na Pesquisa
46.05%
Partial replication is an alluring technique to ensure the reliability of very large and geographically distributed databases while, at the same time, offering good performance. By correctly exploiting access locality most transactions become confined to a small subset of the database replicas thus reducing processing, storage access and communication overhead associated with replication. The advantages of partial replication have however to be weighted against the added complexity that is required to manage it. In fact, if the chosen replica configuration prevents the local execution of transactions or if the overhead of consistency protocols offsets the savings of locality, potential gains cannot be realized. These issues are heavily dependent on the application used for evaluation and render simplistic benchmarks useless. In this paper, we present a detailed analysis of Partial Database State Machine (PDBSM) replication by comparing alternative partial replication protocols with full replication. This is done using a realistic scenario based on a detailed network simulator and access patterns from an industry standard database benchmark. The results obtained allow us to identify the best configuration for typical on-line transaction processing applications.; União Europeia - GORDA Project (FP6-IST/004758).

Partial replication in distributed software transactional memory

Silva, João André Almeida e
Relevância na Pesquisa
46.03%
Dissertação para obtenção do Grau de Mestre em Engenharia Informática; Distributed software transactional memory (DSTM) is emerging as an interesting alternative for distributed concurrency control. Usually, DSTM systems resort to data distribution and full replication techniques in order to provide scalability and fault tolerance. Nevertheless, distribution does not provide support for fault tolerance and full replication limits the system’s total storage capacity. In this context, partial data replication rises as an intermediate solution that combines the best of the previous two trying to mitigate their disadvantages. This strategy has been explored by the distributed databases research field, but has been little addressed in the context of transactional memory and, to the best of our knowledge, it has never before been incorporated into a DSTM system for a general-purpose programming language. Thus, we defend the claim that it is possible to combine both full and partial data replication in such systems. Accordingly, we developed a prototype of a DSTM system combining full and partial data replication for Java programs. We built from an existent DSTM framework and extended it with support for partial data replication. With the proposed framework...

Privacy-preserving tuple matching in distributed databases

Sang, Y.; Shen, H.; Tian, H.
Fonte: IEEE Computer Soc Publicador: IEEE Computer Soc
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.05%
We address the problems of Privacy-Preserving Duplicate Tuple Matching (PPDTM) and Privacy-Preserving Threshold Attributes Matching (PPTAM) in the scenario of a horizontally partitioned database among N parties, where each party holds a private share of the database’s tuples and all tuples have the same set of attributes. In PPDTM, each party determines whether its tuples have any duplicate on other parties’ private databases. In PPTAM, each party determines whether all attribute values of each tuple appear at least a threshold number of times in the attribute unions. We propose protocols for the two problems using additive homomorphic cryptosystem based on the subgroup membership assumption, e.g., Paillier’s and ElGamal’s schemes. By analysis on the total numbers of modular exponentiations, modular multiplications and communication bits, with a reduced computation cost which dominates the total cost, by trading off communication cost, our PPDTM protocol for the semihonest model is superior to the solution derivable from existing techniques in total cost. Our PPTAM protocol is superior in both computation and communication costs. The efficiency improvements are achieved mainly by using random numbers instead of random polynomials as existing techniques for perturbation...

Network application server using Extensible Mark-up Language (XML) to support distributed databases and 3D environments

Williams, Clifton James
Relevância na Pesquisa
46.05%
This thesis contributes to the US Navy forces maintaining information superiority in a Network Centric Warfare environment. This research develops an Extensible Markup Language XML-based Web Publishing Framework, which supports the Web Enabled Navy (WEN) architecture infrastructure. The Web application framework easily supports connections to multiple distributed databases and XML-based presentations, specifically three-dimensional (3D) simulations utilizing Extensible 3D (X3D) and Virtual Reality Modeling Language (VRML). This research evaluates and demonstrates the functionality of an XML-based Web Publishing Framework. The research demonstrates ability to connect to both XML and non-XML heterogeneous database systems and provides a framework for the distribution data across heterogeneous systems. The system supports usage in multi-tier network architecture. 3D modeling and simulations provide insights into operations that cannot be realized using standard two-dimensional (2D) renditions. The development of an application server to support 3D modeling and simulations for operational planning will provide the U.S. Navy a better way of realizing operational limits. This research addresses the Web publishing framework, which supports the development XML based data exchange...

Monitoring and analysis of queries in distributed databases; Monitorização e análise de interrogações em bases de dados distribuídas

Guimarães, Pedro Miguel Pimentel
Relevância na Pesquisa
56.24%
Dissertação de Mestrado em Engenharia Informática; Scalable database services combining multiple technologies, including SQL and NoSQL, are increasingly in vogue. In this context, the CoherentPaaS research project aims at providing an integrated platform with multiple data management technologies, united by a common query language and global transactional coherence. For this integration to succeed, it must provide the same monitoring capabilities of tra ditional relational databases, namely, for database administrators to optimise its operation. However, achieving this in a distributed and heterogeneous system is in itself a challenge. This work proposes a solution to this problem with X-Ray, that allows monitoring code to be added to a Java-based distributed system by manipulating its bytecode at runtime. The resulting information is collected in a NoSQL database and then processed and visualised graphically. This system is evaluated experimentally by adding monitoring to Apache Derby and tested with the standard TPC-C benchmark workload.; Os serviços escaláveis de base de dados combinando diversas tecnologias, incluindo SQL e NoSQL, estão cada vez mais em voga. Neste contexto, o projeto de investigação Coherent PaaS tem como objetivo oferecer uma plataforma integradora de múltiplas tecnologias de gestão de dados...

Heterogeneous Relational Databases for a Grid-enabled Analysis Environment

Ali, Arshad; Anjum, Ashiq; Azim, Tahir; Bunn, Julian; Iqbal, Saima; McClatchey, Richard; Newman, Harvey; Shah, S. Yousaf; Solomonides, Tony; Steenberg, Conrad; Thomas, Michael; van Lingen, Frank; Willers, Ian
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.38%
Grid based systems require a database access mechanism that can provide seamless homogeneous access to the requested data through a virtual data access system, i.e. a system which can take care of tracking the data that is stored in geographically distributed heterogeneous databases. This system should provide an integrated view of the data that is stored in the different repositories by using a virtual data access mechanism, i.e. a mechanism which can hide the heterogeneity of the backend databases from the client applications. This paper focuses on accessing data stored in disparate relational databases through a web service interface, and exploits the features of a Data Warehouse and Data Marts. We present a middleware that enables applications to access data stored in geographically distributed relational databases without being aware of their physical locations and underlying schema. A web service interface is provided to enable applications to access this middleware in a language and platform independent way. A prototype implementation was created based on Clarens [4], Unity [7] and POOL [8]. This ability to access the data stored in the distributed relational databases transparently is likely to be a very powerful one for Grid users...

A Taxonomy of Data Grids for Distributed Data Sharing, Management and Processing

Venugopal, Srikumar; Buyya, Rajkumar; Ramamohanarao, Kotagiri
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46%
Data Grids have been adopted as the platform for scientific communities that need to share, access, transport, process and manage large data collections distributed worldwide. They combine high-end computing technologies with high-performance networking and wide-area storage management techniques. In this paper, we discuss the key concepts behind Data Grids and compare them with other data sharing and distribution paradigms such as content delivery networks, peer-to-peer networks and distributed databases. We then provide comprehensive taxonomies that cover various aspects of architecture, data transportation, data replication and resource allocation and scheduling. Finally, we map the proposed taxonomy to various Data Grid systems not only to validate the taxonomy but also to identify areas for future exploration. Through this taxonomy, we aim to categorise existing systems to better understand their goals and their methodology. This would help evaluate their applicability for solving similar problems. This taxonomy also provides a "gap analysis" of this area through which researchers can potentially identify new issues for investigation. Finally, we hope that the proposed taxonomy and mapping also helps to provide an easy way for new practitioners to understand this complex area of research.; Comment: 46 pages...

Providing an Object Allocation Algorithm in Distributed Databases Using Efficient Factors

Delavar, Arash Ghorbannia; Keshani, Golnoosh
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.21%
Data replication is a common method used to improve the performance of data access in distributed database systems. In this paper, we present an object replication algorithm in distributed database systems (ORAD). We optimize the created replicated data in distributed database systems by using activity functions of previous algorithms, changing them with new technical ways and applying ORAD algorithm for making decisions. We propose ORAD algorithm with using effective factors and observe its results in several valid situations. Our objective is to propose an optimum method that replies read and write requests with less cost in distributed database systems. Finally, we implement ORAD and ADRW algorithms in a PC based network system and demonstrate that ORAD algorithm is superior to ADRW algorithm in the field of average request servicing cost.; Comment: IJCSI International Journal of Computer Science Issues, Vol. 9, Issue 4, No 3, 2012

Using Object-Relational Mapping to Create the Distributed Databases in a Hybrid Cloud Infrastructure

Lukyanchikov, Oleg; Pluzhnik, Evgeniy; Payain, Simon; Nikulchev, Evgeny
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.13%
One of the challenges currently problems in the use of cloud services is the task of designing of specialized data management systems. This is especially important for hybrid systems in which the data are located in public and private clouds. Implementation monitoring functions querying, scheduling and processing software must be properly implemented and is an integral part of the system. To provide these functions is proposed to use an object-relational mapping (ORM). The article devoted to presenting the approach of designing databases for information systems hosted in a hybrid cloud infrastructure. It also provides an example of the development of ORM library.

Intelligent Implementation Processor Design for Oracle Distributed Databases System

Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.2%
Despite the increasing need for modeling and implementing Distributed Databases (DDB), distributed database management systems are still quite far from helping the designer to directly implement its BDD. Indeed, the fundamental principle of implementation of a DDB is to make the database appear as a centralized database, providing series of transparencies, something that is not provided directly by the current DDBMS. We focus in this work on Oracle DBMS which, despite its market dominance, offers only a few logical mechanisms to implement distribution. To remedy this problem, we propose a new architecture of DDBMS Oracle. The idea is based on extending it by an intelligent layer that provides: 1) creation of different types of fragmentation through a GUI for defining different sites geographically dispersed 2) allocation and replication of DB. The system must automatically generate SQL scripts for each site of the original configuration.

Consistent Checkpointing in Distributed Databases: Towards a Formal Approach

Baldoni, R.; Quaglia, F.; Raynal, M.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.11%
Whether it is for audit or for recovery purposes, data checkpointing is an important problem of distributed database systems. Actually, transactions establish dependence relations on data checkpoints taken by data object managers. So, given an arbitrary set of data checkpoints (including at least a single data checkpoint from a data manager, and at most a data checkpoint from each data manager), an important question is the following one: Can these data checkpoints be members of a same consistent global checkpoint?''. This paper answers this question by providing a necessary and sufficient condition suited for database systems. Moreover, to show the usefulness of this condition, two {\em non-intrusive} data checkpointing protocols are derived from this condition. It is also interesting to note that this paper, by exhibiting correspondences'', establishes a bridge between the data object/transaction model and the process/message-passing model.; Comment: 13 pages, 3 figures

Distributed Kernel Regression: An Algorithm for Training Collaboratively

Predd, Joel B.; Kulkarni, Sanjeev R.; Poor, H. Vincent
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.05%
This paper addresses the problem of distributed learning under communication constraints, motivated by distributed signal processing in wireless sensor networks and data mining with distributed databases. After formalizing a general model for distributed learning, an algorithm for collaboratively training regularized kernel least-squares regression estimators is derived. Noting that the algorithm can be viewed as an application of successive orthogonal projection algorithms, its convergence properties are investigated and the statistical behavior of the estimator is discussed in a simplified theoretical setting.; Comment: To be presented at the 2006 IEEE Information Theory Workshop, Punta del Este, Uruguay, March 13-17, 2006

Review on Fragment Allocation by using Clustering Technique in Distributed Database System

Dash, Priyanka; Rout, Ranjita; Pratihari, Satya Bhusan; Padhi, Sanjay Kumar
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.21%
Considerable Progress has been made in the last few years in improving the performance of the distributed database systems. The development of Fragment allocation models in Distributed database is becoming difficult due to the complexity of huge number of sites and their communication considerations. Under such conditions, simulation of clustering and data allocation is adequate tools for understanding and evaluating the performance of data allocation in Distributed databases. Clustering sites and fragment allocation are key challenges in Distributed database performance, and are considered to be efficient methods that have a major role in reducing transferred and accessed data during the execution of applications. In this paper a review on Fragment allocation by using Clustering technique is given in Distributed Database System.; Comment: 9 pages,3 figures

Mining The Data From Distributed Database Using An Improved Mining Algorithm

Renjit, J. Arokia; Shunmuganathan, K. L.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.27%
Association rule mining is an active data mining research area and most ARM algorithms cater to a centralized environment. Centralized data mining to discover useful patterns in distributed databases isn't always feasible because merging data sets from different sites incurs huge network communication costs. In this paper, an Improved algorithm based on good performance level for data mining is being proposed. In local sites, it runs the application based on the improved LMatrix algorithm, which is used to calculate local support counts. Local Site also finds a centre site to manage every message exchanged to obtain all globally frequent item sets. It also reduces the time of scan of partition database by using LMatrix which increases the performance of the algorithm. Therefore, the research is to develop a distributed algorithm for geographically distributed data sets that reduces communication costs, superior running efficiency, and stronger scalability than direct application of a sequential algorithm in distributed databases.; Comment: IEEE Publication format, International Journal of Computer Science and Information Security, IJCSIS, Vol. 7 No. 3, March 2010, USA. ISSN 1947 5500, http://sites.google.com/site/ijcsis/

Secure Mining of Association Rules in Horizontally Distributed Databases

Tassa, Tamir
Tipo: Artigo de Revista Científica