• Title/Summary/Keyword: skyline

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An Efficient MapReduce-based Skyline Query Processing Method with Two-level Grid Blocks (2-계층 그리드 블록을 이용한 효과적인 맵리듀스 기반 스카이라인 질의 처리 기법)

  • Ryu, Hyeongcheol;Jung, Sungwon
    • Journal of KIISE
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    • v.44 no.6
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    • pp.613-620
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    • 2017
  • Skyline queries are used extensively to solve various problems, such as in decision-making, because they find data that meet a variety of user criteria. Recent research has focused on skyline queries by using the MapReduce framework for large database processing, mainly in terms of applying existing index structures to MapReduce. In a skyline, data closer to the origin dominate more area. However, the existing index structure does not reflect such characteristics of the skyline. In this paper, we propose a grid-block structure that groups grid cells to match the characteristics of a skyline, and a two-level grid-block structure that can be used even when there are no data close to the origin. We also propose an efficient skyline-query algorithm that uses the two-level grid-block structure.

An Efficient Angular Space Partitioning Based Skyline Query Processing Using Sampling-Based Pruning (데이터 샘플링 기반 프루닝 기법을 도입한 효율적인 각도 기반 공간 분할 병렬 스카이라인 질의 처리 기법)

  • Choi, Woosung;Kim, Minseok;Diana, Gromyko;Chung, Jaehwa;Jung, Soonyong
    • KIPS Transactions on Software and Data Engineering
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    • v.6 no.1
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    • pp.1-8
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    • 2017
  • Given a multi-dimensional dataset of tuples, a skyline query returns a subset of tuples which are not 'dominated' by any other tuples. Skyline query is very useful in Big data analysis since it filters out uninteresting items. Much interest was devoted to the MapReduce-based parallel processing of skyline queries in large-scale distributed environment. There are three requirements to improve parallelism in MapReduced-based algorithms: (1) workload should be well balanced (2) avoid redundant computations (3) Optimize network communication cost. In this paper, we introduce MR-SEAP (MapReduce sample Skyline object Equality Angular Partitioning), an efficient angular space partitioning based skyline query processing using sampling-based pruning, which satisfies requirements above. We conduct an extensive experiment to evaluate MR-SEAP.

Reverse Skyline Query Processing for Region Objects (영역객체를 위한 리버스 스카이라인 질의 처리)

  • Han, Ah;Li, Zhong-He;Park, Young-Bae
    • Journal of KIISE:Databases
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    • v.37 no.4
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    • pp.185-196
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    • 2010
  • Existing methods to compute reverse skyline queries are not correct to process the queries in dataset with region objects which have conditions like a price is 5~7 dollars and a distance to beach is 1km~2km, since they consider datasets with only point objects. To solve the problem, we propose a novel method to process reverse skyline queries for region objects in this paper. It has advantages. First, it is expected to get a good performance, because it is extended from efficient reverse skyline (ERSL) algorithm which is a best algorithm to computing reverse skyline queries in datasets with point objects. Second, it can give a right of choice unlike the others to a person requesting the query. That is because results of reverse skyline have a difference preference according to proposed pruning methods and overlap relations. This algorithm is a first for supporting region objects. Therefore there are not any other algorithms to compare their performance. For that reason, our experiment to prove the efficiency of proposed algorithm is focused what conditions give an effect to its performance and result and how much time it needs to process the query.

Computing the Skyline of Moving Query Points in $L_1$ metric ($L_1$ 메트릭에서의 이동 질의점에 대한 skyline 계산)

  • Son, Wan-Bin;Hwang, Seung-Won;Ahn, Hee-Kap
    • Proceedings of the Korean Information Science Society Conference
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    • 2012.06a
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    • pp.388-390
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    • 2012
  • 본 논문에서는 $L_1$ 메트릭을 사용하는 평면상에 주어진 자료점의 집합 P로부터 질의점의 집합 Q에 대해 skyline이 되는 점들을 계산하는 문제를 다룬다. $L_1$ 거리는 도로망이 잘 발달된 도시 내의 이동 시간을 근사화해 주는 것으로 알려져 있다. 이 문제에서 각각의 질의점은 수직 또는 수평 방향으로 단위속도로 움직인다고 가정한다. 본 논문에서는 시간 0에서 $t_1$ 사이에 움직이는 질의점들에 대해서 skyline의 변화를 모두 계산하는 알고리즘을 제시한다. 또한 이 알고리즘이 O(${\mid}P{\mid}^2{\mid}Q{\mid}$) 시간에 모든 skyline을 계산 가능함을 보인다.

Skyline Algorithm for Finite Analysis Programs Written in C Language (C언어의 유한요소해석 프로그램을 위한 Skyline Algorithm)

  • 이재영
    • Computational Structural Engineering
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    • v.2 no.2
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    • pp.85-92
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    • 1989
  • A modified skyline algorithm suitable for C language in this paper. The modified algorithm improves the computational efficiency and the structure of the program. Substantial reduction of execution time is achieved by simplifying assemblage and decomposition of the stiffness matrix. A source program is also provided for use in future development of finite element softwares.

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A Problem Analysis of Skyline Queries using Space Partitioning Techniques (공간 분할 방법을 사용하는 Skyline 질의 방법의 문제점 비교 분석)

  • Ihm, Sun-Young;Park, Eun-Young;Park, Young-Ho
    • Proceedings of the Korea Information Processing Society Conference
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    • 2012.11a
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    • pp.1382-1384
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    • 2012
  • 최근 대용량 혹은 복잡한 데이터에서의 빠른 검색을 돕는 Skyline 질의 처리에 대한 관심이 높아지고 있으며, 많은 응용프로그램에서 사용되고 있다. Skyline 질의는 데이터베이스의 튜플들을 공간상으로 표현하여 질의 처리를 할 수 있는 데, 이 때 빠른 처리를 위하여 공간 분할 기법이 사용된다. 본 논문에서는 공간 분할 기법을 사용한 Skyline 질의 방법들을 소개하고 문제점을 분석한다. 또한, 문제점 해결 방안을 함께 제시하며 기대 효과를 예측한다.

An Efficient Pruning Method for Subspace Skyline Queries of Moving Objects (이동 객체의 부분차원 스카이라인 질의를 위한 효율적인 가지치기 기법)

  • Kim, Jin-Ho;Park, Young-Bae
    • Journal of KIISE:Databases
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    • v.35 no.2
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    • pp.182-191
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    • 2008
  • Most of previous works for skyline queries have focused only on static attributes of target objects. With the advance in mobile applications, however, the need of continuous skyline queries for moving objects has been increasing. Even though several techniques to process continuous skyline queries have been proposed recently, they cannot process subspace queries, which use only the subset of attribute dimensions. Therefore it is not feasible to utilize those methods for mobile applications which must consider moving objects and subspaces simultaneously. In this paper, we propose a dominant object-based pruning method to compute subspace skyline of moving objects efficiently at query time and present the experimental results to show the effectiveness of the proposed method.

Skyline Query Algorithm in the Categoric Data (범주형 데이터에 대한 스카이라인 질의 알고리즘)

  • Lee, Woo-Key;Choi, Jung-Ho;Song, Jong-Su
    • Journal of KIISE:Computing Practices and Letters
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    • v.16 no.7
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    • pp.819-823
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    • 2010
  • The skyline query is one of the effective methods to deal with the large amounts and multi-dimensional data set. By utilizing the concept of 'dominate' the skyline query can pinpoint the target data so that the dominated ones, about 95% of them, can efficiently be excluded as an unnecessary data. Most of the skyline query algorithms, however, have been developed in terms of the numerical data set. This paper pioneers an entirely new domain, the categorical data, on which the corresponding ranking measures for the skyline queries are suggested. In the experiment, the ACM Computing Classification System has been exploited to which our methods are significantly represented with respect to performance thresholds such as the processing time and precision ratio, etc.

Efficient Continuous Skyline Query Processing Scheme over Large Dynamic Data Sets

  • Li, He;Yoo, Jaesoo
    • ETRI Journal
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    • v.38 no.6
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    • pp.1197-1206
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    • 2016
  • Performing continuous skyline queries of dynamic data sets is now more challenging as the sizes of data sets increase and as they become more volatile due to the increase in dynamic updates. Although previous work proposed support for such queries, their efficiency was restricted to small data sets or uniformly distributed data sets. In a production database with many concurrent queries, the execution of continuous skyline queries impacts query performance due to update requirements to acquire exclusive locks, possibly blocking other query threads. Thus, the computational costs increase. In order to minimize computational requirements, we propose a method based on a multi-layer grid structure. First, relational data object, elements of an initial data set, are processed to obtain the corresponding multi-layer grid structure and the skyline influence regions over the data. Then, the dynamic data are processed only when they are identified within the skyline influence regions. Therefore, a large amount of computation can be pruned by adopting the proposed multi-layer grid structure. Using a variety of datasets, the performance evaluation confirms the efficiency of the proposed method.

Multi-Dimensional Traveling Salesman Problem Scheme Using Top-n Skyline Query (Top-n 스카이라인 질의를 이용한 다차원 외판원 순회문제 기법)

  • Jin, ChangGyun;Oh, Dukshin;Kim, Jongwan
    • KIPS Transactions on Software and Data Engineering
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    • v.9 no.1
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    • pp.17-24
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    • 2020
  • The traveling salesman problem is an algorithmic problem tasked with finding the shortest route that a salesman visits, visiting each city and returning to the started city. Due to the exponential time complexity of TSP, it's hard to implement on cases like amusement park or delivery. Also, TSP is hard to meet user's demand that is associated with multi-dimensional attributes like travel time, interests, waiting time because it uses only one attribute - distance between nodes. This paper proposed Top-n Skyline-Multi Dimension TSP to resolve formerly adverted problems. The proposed algorithm finds the shortest route faster than the existing method by decreasing the number of operations, selecting multi-dimensional nodes according to the dominance of skyline. In the simulation, we compared computation time of dynamic programming algorithm to the proposed a TS-MDT algorithm, and it showed that TS-MDT was faster than dynamic programming algorithm.