24,821 research outputs found

    Stochastic Database Cracking: Towards Robust Adaptive Indexing in Main-Memory Column-Stores

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    Modern business applications and scientific databases call for inherently dynamic data storage environments. Such environments are characterized by two challenging features: (a) they have little idle system time to devote on physical design; and (b) there is little, if any, a priori workload knowledge, while the query and data workload keeps changing dynamically. In such environments, traditional approaches to index building and maintenance cannot apply. Database cracking has been proposed as a solution that allows on-the-fly physical data reorganization, as a collateral effect of query processing. Cracking aims to continuously and automatically adapt indexes to the workload at hand, without human intervention. Indexes are built incrementally, adaptively, and on demand. Nevertheless, as we show, existing adaptive indexing methods fail to deliver workload-robustness; they perform much better with random workloads than with others. This frailty derives from the inelasticity with which these approaches interpret each query as a hint on how data should be stored. Current cracking schemes blindly reorganize the data within each query's range, even if that results into successive expensive operations with minimal indexing benefit. In this paper, we introduce stochastic cracking, a significantly more resilient approach to adaptive indexing. Stochastic cracking also uses each query as a hint on how to reorganize data, but not blindly so; it gains resilience and avoids performance bottlenecks by deliberately applying certain arbitrary choices in its decision-making. Thereby, we bring adaptive indexing forward to a mature formulation that confers the workload-robustness previous approaches lacked. Our extensive experimental study verifies that stochastic cracking maintains the desired properties of original database cracking while at the same time it performs well with diverse realistic workloads.Comment: VLDB201

    Integration of Exploration and Search: A Case Study of the M3 Model

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    International audienceEffective support for multimedia analytics applications requires exploration and search to be integrated seamlessly into a single interaction model. Media metadata can be seen as defining a multidimensional media space, casting multimedia analytics tasks as exploration, manipulation and augmentation of that space. We present an initial case study of integrating exploration and search within this multidimensional media space. We extend the M3 model, initially proposed as a pure exploration tool, and show that it can be elegantly extended to allow searching within an exploration context and exploring within a search context. We then evaluate the suitability of relational database management systems, as representatives of today’s data management technologies, for implementing the extended M3 model. Based on our results, we finally propose some research directions for scalability of multimedia analytics

    Filtering speed in a continental European reorganization procedure.

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    Recent studies of U.S. Chapter 11 show it to be a relatively efficient procedure. We examine reorganization cases in a Continental European, creditor-oriented bankruptcy system, viz. Belgium, and report very different findings. Using hazard and cure regression models to determine what drives the length of time spent in reorganizations, we find evidence suggesting that courts have little impact on the screening and filtering process. In fact, virtually all drivers of procedure length prove to have the opposite sign of what one would expect if the procedure would efficiently realise its goals. Instead, the procedure appears to be mainly creditor driven.Reorganization; Bankruptcy; Hazard models; Filtering speed;

    Usages of the internet and e-tourism. Towards a new economy of tourism

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    This paper analyses the impact of internet on the organization of industry and the marketdynamics in the tourism activities, focusing in the European scene. Tourism incorporates many features ofthe contemporaneous information and communication economy. Even if e-tourism still stands for a smallshare of the whole tourism activity, the paper establishes that the internet basically explains theorganization of the activities and markets that emerge today. A relevant analytical framework able toapprehend these dynamics is first defined. The concept of sectoral system of production and innovation isshown to provide a relevant analytical framework to grasp the basic changes of the tourism industry. Thepaper enlightens on this basis the evolution resulting from the emergence of e-tourism and the uses ofinternet, their impacts on the coordination of the activities and the markets, with a special focus on theEuropean caseTourism; Sectoral Systems of Production and Innovation;ICT; Virtual Communities; GDS

    A database management capability for Ada

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    The data requirements of mission critical defense systems have been increasing dramatically. Command and control, intelligence, logistics, and even weapons systems are being required to integrate, process, and share ever increasing volumes of information. To meet this need, systems are now being specified that incorporate data base management subsystems for handling storage and retrieval of information. It is expected that a large number of the next generation of mission critical systems will contain embedded data base management systems. Since the use of Ada has been mandated for most of these systems, it is important to address the issues of providing data base management capabilities that can be closely coupled with Ada. A comprehensive distributed data base management project has been investigated. The key deliverables of this project are three closely related prototype systems implemented in Ada. These three systems are discussed

    Fusing drug enforcement: a study of the El Paso Intelligence Center

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    This article examines the evolution of the El Paso Intelligence Center (EPIC), a key intelligence component of the Drug Enforcement Administration, to shed light on fusion efforts in drug enforcement. Since 1974, EPIC has strived to fuse the resources and capabilities of multiple government agencies to counter drug trafficking and related threats along the Southwest US border. While undergoing a steady growth, the Center has confronted a host of challenges that illuminate the uses and limits of multi-agency endeavors in drug enforcement. An evaluative study of the Center shows that it is well aligned with the federal government priorities in the realm of drug enforcement; however the extent to which the Center’s activities support the government’s efforts in this domain is not so clear. The Center needs to improve the way it reviews its own performance to better adapt and serve its customers

    Parallelizing Windowed Stream Joins in a Shared-Nothing Cluster

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    The availability of large number of processing nodes in a parallel and distributed computing environment enables sophisticated real time processing over high speed data streams, as required by many emerging applications. Sliding window stream joins are among the most important operators in a stream processing system. In this paper, we consider the issue of parallelizing a sliding window stream join operator over a shared nothing cluster. We propose a framework, based on fixed or predefined communication pattern, to distribute the join processing loads over the shared-nothing cluster. We consider various overheads while scaling over a large number of nodes, and propose solution methodologies to cope with the issues. We implement the algorithm over a cluster using a message passing system, and present the experimental results showing the effectiveness of the join processing algorithm.Comment: 11 page
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