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41st International Symposium on Reliable distributed Systems (SRDS)

作者： Waudby, Jack Ezhilchelvan, Paul Mitrani, Isi Webber, Jim Newcastle Univ Newcastle Upon Tyne Tyne & Wear England Neo4j San Mateo CA USA

ISBN: (纸本)9781665497534

distributed OLTP systems execute the high-overhead, two-phase commit (2PC) protocol at the end of every distributed transaction. Epoch-based commit proposes that 2PC be executed only once for all transactions processed within a time interval called an epoch. Increasing epoch duration allows more transactions to be processed before the common 2PC. It thus reduces 2PC overhead per transaction, increases throughput but also increases average transaction latency. Therefore, required is the ability to choose the right epoch size that offers the desired trade-off between throughput and latency. To this end, we develop two analytical models to estimate throughput and average latency in terms of epoch size taking into account load and failure conditions. Simulations affirm their accuracy and effectiveness. We then present epoch-based multi-commit which, unlike epoch-based commit, seeks to avoid all transactions being aborted when failures occur, and also performs identically when failures do not occur. Our performance study identifies workload factors that make it more effective in preventing transaction aborts and concludes that the analytical models can be equally useful in predicting its performance as well.

关键词： distributed databases Transactions Two-Phase Commit Epochs Analytical solutions Simulations Performance Evaluation Throughput Latency

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Smart Colonography for distributed Medical databases with Group Kernel Feature Analysis

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ACM TRANSACTIONS ON INTELLIGENT SYSTEMS AND TECHNOLOGY 2015年第4期6卷 58-58页

作者： Motai, Yuichi Ma, Dingkun Docef, Alen Yoshida, Hiroyuki Virginia Commonwealth Univ Dept Elect & Comp Engn Richmond VA 23284 USA Massachusetts Gen Hosp Dept Radiol Boston MA 02114 USA Harvard Univ Sch Med Boston MA 02114 USA

Computer-Aided Detection (CAD) of polyps in Computed Tomographic (CT) colonography is currently very limited since a single database at each hospital/institution doesn't provide sufficient data for training the CAD system's classification algorithm. To address this limitation, we propose to use multiple databases, (e.g., big data studies) to create multiple institution-wide databases using distributed computing technologies, which we call smart colonography. Smart colonography may be built by a larger colonography database networked through the participation of multiple institutions via distributed computing. The motivation herein is to create a distributed database that increases the detection accuracy of CAD diagnosis by covering many true-positive cases. Colonography data analysis is mutually accessible to increase the availability of resources so that the knowledge of radiologists is enhanced. In this article, we propose a scalable and efficient algorithm called Group Kernel Feature Analysis (GKFA), which can be applied to multiple cancer databases so that the overall performance of CAD is improved. The key idea behind the proposed GKFA method is to allow the feature space to be updated as the training proceeds with more data being fed from other institutions into the algorithm. Experimental results show that GKFA achieves very good classification accuracy.

关键词： Algorithms Computed tomographic colonography distributed databases kernel feature analysis group learning

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Authenticated Top-K Aggregation in distributed and Outsourced databases

Authenticated Top-K Aggregation in Distributed and Outsource...

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IEEE International Conference on and IEEE International Confernece on Social Computing (SocialCom) Privacy, Security, Risk and Trust (PASSAT)

作者： Sunoh Choi Hyo-Sang Lim Elisa Bertino ECE Department Purdue University West Lafayette IN USA CTE Division Yonsei University Wonju Kangwon Korea CS Department Purdue University West Lafayette IN USA

Top-k queries have attracted interest in many different areas like network and system monitoring, information retrieval, sensor networks, and so on. Since today many applications issue top-k queries on distributed and outsourced databases, authentication of top-k query results becomes more important. This paper addresses the problem of authenticated top-k aggregation queries (e.g. “find the k objects with the highest aggregate values”) in a distributed system. We propose a new algorithm, called Authenticated Three Phase Uniform Threshold (A-TPUT), which provides not only efficient top-k aggregation over distributed databases but also authentication on the top-k results. We also introduce several enhancements for A-TPUT to reduce both the computation cost and the communication cost. Finally, we confirm the efficiency of our solutions through an extensive experimental evaluation.

关键词： Digital signal processing distributed databases Authentication Algorithm design and analysis Aggregates Upper bound

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Content-based retrieval of 3D models in distributed Web databases by visual shape information

Content-based retrieval of 3D models in distributed Web data...

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International Conference on Information Visualisation (IV)

作者： J. Loffler Nat. Res. Center for Inf. Technol. Sankt Augustin Germany

Digital documents assembled from different components, like text, images, video, audio and 3D models, are supported today by many distributed applications. This paper presents a new approach to retrieving 3D models as part of digital documents using content-based image retrieval functionality. To find a 3D model best-fitting the user's query, shape information is extracted from the retrieved models and a score is generated by comparing shape images with the graphical user input. A distributed database environment with a WWW interface is presented and used as a generic implementation platform for this technique. The new retrieval method for 3D geometry is then described by extending the generic architecture in two steps, with a server-side module and an interactive client display. I outline how this method can be used for partial geometry downloading of 3D models in digital libraries.

关键词： Information retrieval Content based retrieval distributed databases Image retrieval Image databases Shape Geometry Assembly Data mining Spatial databases

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Performance comparison of distributed in memory databases in dynamic fog environments

Performance comparison of distributed in memory databases in...

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IEEE International Conference on Big Data and Cloud Computing (BdCloud)

作者： George Vlahavas Anna-Valentini Michailidou Theodoros Toliopoulos Vasileios G. Psomiadis Anastasios Gounaris Athena Vakali School of Informatics Aristotle University of Thessaloniki Thessaloniki Greece

Fog computing is an extension of cloud computing to overcome limitations of the latter. It brings data processing and storage closer to edge devices, while offering higher processing power and storage space compared to the edge. In edge or fog environments, data is often ephemeral, so storing data in memory provides considerable performance benefits. Edge or fog nodes may also fail or disconnect, so distributed database systems are used in order to provide durability and availability. Database performance is an important factor when designing a fog platform. We assess the performance of two distributed, in memory databases, Apache Ignite and Redis, measured as throughput, with respect to different parameters: number of nodes, number of replicas, persistency, network bandwidth, network latency and number of operations. In all cases, Redis outperforms Apache Ignite, however, Apache Ignite scales very well when the number of operations is increased.

关键词： Performance evaluation Degradation Cloud computing distributed databases Bandwidth Benchmark testing Throughput

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A New Data Communication Protocol for distributed Mobile databases in Mobile Ad Hoc Networks

A New Data Communication Protocol for Distributed Mobile Dat...

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International Conference on Information Technology: New Generations (ITNG)

作者： Afsaneh Rahbar Mehran Mohsenzadeh Amir Masoud Rahmani Department of Computer-Engineering Islamic Azad University Tehran Iran

ISBN: (纸本)9781424437702

Three data communication methods can be provided in a MANET: data broadcast, data query, and peer-to-peer messaging. The formation of heterogeneous distributed mobile databases within a MANET that allows people to submit queries is becoming a reality. The goal of this paper is to integrate distributed mobile databases in MANETs and proposes a new data communication protocol that supports all three modes of data communication in the network region and allows mobile applications to view these separate non identical databases as one integrated database. This protocol adjusts node disconnection and reconnection through periodic synchronization. In this distributed database framework mobile servers comprise Data Directories (DDs) that gather and store the schemas of mobile databases running on detected mobile devices in the service cycle. DDs inform the requesting node whether a submitted query is answerable from participating mobile database nodes or not. Also this protocol allows mobile nodes of the architecture to exchange messages for the purpose of executing the submitted query against the distributed mobile database and then returning the results.

关键词： Data communication Protocols distributed databases Mobile ad hoc networks Peer to peer computing Mobile computing Broadcasting Database systems Computer networks distributed computing

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Processing Location Dependent Continuous Queries in distributed Mobile databases using Mobile Agents

Processing Location Dependent Continuous Queries in Distribu...

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International Conference on Signal Processing, Communication and Networking (ICSCN)

作者： M. Vijayalakshmi A. Kannan Department of Computer Science and Engineering College of Engineering Anna University Chennai India

With the increase in the number of mobile users, the need for new type of services and applications is also on the rise. Particularly, a growing area of interest is to provide location dependent services to the mobile users. In this paper, we present a system that supports distributed processing of location-dependent continuous queries on distributed mobile data in a mobile environment using mobile agents. We investigate a scenario in which both the querying unit and the object being queried (target object) are capable of movement and the mobile unit is equipped with more powerful capabilities, including the storage of a small database and the capacity of data processing. Since our system deals with continuous queries, we propose a shared incremental update mechanism, which caches the results of the previously evaluated queries and avoids redundant results thereby minimizing the data traffic in wireless environment. To further reduce the data transfer we share the cached data among different queries. Our system uses mobile agents for evaluating queries, which involves data from both the server and mobile unit, and it helps in parallel processing of data and it, can efficiently track the mobile units involved in the system. The conventional query processing method like join processing of data from mobile units and server is directly applied in the mobile environment.

关键词： distributed databases Mobile agents Mobile computing Data engineering Query processing Wireless networks Signal processing Mobile communication Computer science Educational institutions

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A performance comparison between parallel and lazy fetching in vertically distributed cloud databases

A performance comparison between parallel and lazy fetching ...

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International Conference on Cloud Technologies and Applications (CloudTech)

作者： Jens Kohler Thomas Specht University of Applied Sciences Institute for Enterprise Computing Mannheim Germany

The following work focuses on the severe performance issues that come along with the vertical data distribution approach of the SeDiCo framework. SeDiCo (A Secure and distributed Cloud Data Store) is a framework that vertically distributes database data across several clouds in order to maintain data security, protection and privacy. However, this vertical data distribution requires joining data together before any client access. This join is extremely time-consuming and thus, this approach is currently not feasible in practical usage scenarios. In order to overcome those performance issues, this work proposes the introduction of a data cache architecture and two corresponding fetch procedures, i.e. lazy and parallel fetching. We further implemented both strategies, measured their performance and compared them to each other. Our results show that the parallel fetch strategy by far outperforms the lazy fetch strategy. Above that, this work outlines the entire caching architecture of our approach and discusses the two strategies in detail. Finally, this work concludes the measured results and discusses further challenges in the context of the SeDiCo framework as future work tasks.

关键词： distributed databases Cloud computing Computer architecture Data privacy Data security Performance evaluation

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distributed architectures and databases for intelligent personal communication networks

Distributed architectures and databases for intelligent pers...

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Wireless Communications Conference

作者： L.J. Ng R.W. Donaldson A.D. Malyan Department of Electrical Engineering University of British Columbia Vancouver BC Canada

The provision of advanced network services for personal communications is dependent upon the intelligent network (IN). The physical location of IN service control logic and databases in the personal communication network (PCN) substantially affects the signalling and processing delay and is considered critical given the anticipated demand for PCS. The authors propose a MAN hierarchical design for network intelligence which avoids the traffic congestion associated with subscriber registration and call setup inherent in a centralized approach.< >

关键词： distributed databases Deductive databases Intelligent networks Personal communication networks Spine Parallel processing Communication system control Logic Signal processing Communication system traffic control

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Robust Service-Based Semantic Querying to distributed Heterogeneous databases

Robust Service-Based Semantic Querying to Distributed Hetero...

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International Workshop on Database and Expert Systems Applications

作者： Carlos Buil-Aranda Óscar Corcho Amy Krause Ontology Engineering Group Departamento de Inteligencia Artificial Universidad Politécnica de Madrid Madrid Spain EPCC University of Edinburgh Edinburgh UK

The amount of semantic data on the Web has increased exponentially in the last years. One of the main reasons for this is the use of RDB2RDF systems, which generate RDF data from relational databases. Most of the work on these systems has focused on increasing the expressivity of query languages, analyzing their coverage over databases and generating sound, complete and efficient query plans. However, there are still important problems associated to them, especially in terms of robustness and in the handling of data distribution. In this paper we describe how we have integrated one RDB2RDF system (ODEMapster) with OGSA-DAI in order to overcome these problems.

关键词： Robustness distributed databases Relational databases Resource description framework Ontologies Database languages Spatial databases Data mining Expert systems Data engineering

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