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Due to the coarse granularity of data accesses and the heavy use of latches, indices in the B-tree family are not efficient for in-memory databases, especially in the context of today's multi-core architecture. In this paper, we study the parallelizability of skip lists for the parallel and concurrent environment, and present PSL, a Parallel in-memory Skip List that lends itself naturally to the multi-core...
We define and study Euclidean and spatial network variants of a new path finding problem: given a set of safe zones, find paths that minimize the distance traveled outside the safe zones. In this problem, the entire space with the exception of the safe zones is unsafe, but passable, and it differs from problems that involve unsafe regions to be strictly avoided. As a result, existing algorithms are...
Peer-to-peer systems have recently achieved a remarkable success in the social, academic and commercial communities. In P2P systems, a very large number of autonomous computing peers pool together their resources and rely on each other for any request. A fundamental problem in Peer-to-Peer networks is how to locate efficiently appropriate peers to answer a specific query (Query routing). A lot of...
Distributed solutions for the storage and retrieval of large amounts of data are necessary to handle the growing amounts of knowledge expected from future applications. The support for range queries provides much-needed expressivity, for example for queries on data annotated with location and time. We present a novel and scalable way for range query evaluation in our distributed storage system based...
P2P technology provides new views for data integration purposes. In P2P systems, there is no global knowledge, neither a global schema nor information of data distribution or indices. An important issue in the context of schema-based P2P systems is efficient query processing. Because of the lack of global knowledge, query planning is much more difficult than in centralized systems. In this paper,...
Small-World paradigm was adopted by many peer-to-peer (P2P) systems such as Freenet in order to improve performance of the P2P system. To adopt Small world as part of the architecture of a P2P system, the overlay network must achieve high cluster coefficient and low average hop between any two randomly chosen peers. In this research, we propose to enhance the overlay network by incorporating the concept...
Small-World paradigm was adopted by many peer-to-peer (P2P) systems such as Freenet in order to improve performance of the P2P system. To adopt Small world as part of the architecture of a P2P system, the overlay network must archive high cluster coefficient and low average hop between any two randomly chosen peers. In this research, we propose to enhance Limewire by incorporating the Small world...
The complex multi-attribute query processing in the large-scale distributed systems is a research topic focused by both academia and industry. This paper introduces a common architecture of the multi-dimensional data range queries based on the P2P network and constructs a virtual hierarchical tree based on space division which ensures that the exploration of the relevant query regions occurred between...
In traditional P2P networks, such as Gnutella, peers propagate query messages towards the resource holders by flooding them through the network. However, it is a costly operation since it consumes node and link resources excessively, which are often unnecessarily. There is no reason, for example, for a peer to receive a query message if the peer has no matching resource or is not on the path to a...
The sciences, business confederations, and medicine urgently need infrastructure for sharing data and updates among collaborators' constantly changing, heterogeneous databases. The ORCHESTRA system addresses these needs by providing data transformation and exchange capabilities across DBMSs, combined with archived storage of all database versions. ORCHESTRA adopts a peer-to-peer architecture in which...
Existing methods and techniques utilized by peer-to-peer (P2P) systems could address the scalability issue faced by grid systems. Today's Grid systems have to deal with potentially a large number of resources which their status changes over time. Therefore, accurate, fast and scalable discovery of resources are key issues that Grid systems should deal with. Typical P2P systems enable sharing static...
This paper presents the design of a decentralized storage scheme to support multi-dimensional range queries over sensor networks. We build a distributed k-d tree based index structure over sensor network, so as to efficiently map high dimensional event data to a two-dimensional space of sensors while preserving the proximity of events. We propose a dynamic programming based methodology to control...
Resource discovery is critical to the usability and accessibility of grid computing systems. Distributed hash table (DHT) has been applied to grid systems as a distributed mechanism for providing scalable range-query and multiattribute resource discovery. Multi-DHT-based approaches depend on multiple DHT networks with each network responsible for a single attribute. Single-DHT-based approaches keep...
The multidimensional similarity query, an essential query for information processing in sensor networks, has not received sufficient attention in the research community of sensor networks. In this paper, we study the multidimensional similarity query for large-scale sensor networks and propose a new algorithm called DIC (dimension reduction by Chebyshev polynomials). In DIC algorithm, the normalized...
Range query in Peer-to-Peer networks based on Distributed Hash Table (DHT) is still an open problem. The traditional way uses order-preserving hashing functions to create value indexes that are placed and stored on the corresponding peers to support range query. The way, however, suffers from high index maintenance costs. To avoid the issue, a scalable blind search method over DHTs - recursive partition...
Efficient file query is important to the overall performance of peer-to-peer (P2P) file sharing systems. Clustering peers by their common interests can significantly enhance the efficiency of file query. On the other hand, clustering peers by their physical proximity can also improve file query performance. Few current works are able to cluster peers based on both peer interest and physical proximity...
In recent years, the issue of heterogeneity and data sharing has been discussed in different contexts and according to diverse points of view. However, we can retain especially two significant axes which are data integration and P2P computing. Data integration aims to hide heterogeneities of distributed sources. However, most of data integration solutions are centralized-based architecture. The birth...
In this paper we propose a new architecture based on Z-order curve and kd-tree that can efficiently handle issues related to update messages distribution to interested entities locations in a three-dimensional (3D) virtual environments where locations are described in terms of 3D coordinates. We also aim to minimize the number of routing hops in distribution of update messages, especially when updates...
Effectiveness of P2P systems highly depends on efficiency of their search algorithms. With existence of malicious and dishonest nodes, reputation systems are essential to evaluate the trustworthiness of participating peers and to combat subversive peer behaviors. Surprisingly majority of the available reputation systems, ignore the underlying search algorithm and assume it pre-existing. In this paper...
Similarity searching is particularly important in distributed networks such as P2P systems, which use various routing schemes to submit queries to relevant peers. We investigate content-based information routing and retrieval using similarity search in clustered P2P overlay networks and focus on their maintenance cost models and performance issues. We present a query model for a cluster based P2P...
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