Z-SKY: an efficient skyline query processing framework based on Z-order

Lee, Ken C.; Lee, Wang-Chien; Zheng, Baihua; Li, Huajing; Tian, Yuan

doi:10.1007/s00778-009-0166-x

Cited by 87 publications

(37 citation statements)

References 22 publications

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“…Since large volumes of data records stored on disks, various efficient disk-based algorithms are derived. Representative ones include Bitmap [19], BNL [4], Index [19], NN [12], BBS [16], Presorting [6], and Z-SKY [13]. Among those, index-based search algorithms, namely, NN, BBS and Z-SKY generally provide better search performance.…”

Section: Related Workmentioning

confidence: 99%

Efficient evaluation of location-dependent skyline queries using non-dominance scopes

Lee

2011

Proceedings of the 2nd International Conference on Computing for Geospatial Research &Amp; Applications - COM.Geo '11

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With respect to a given query point q, a location-dependent skyline query (LDSQ) finds all objects that are not spatially dominated by any other in a specified set of objects. An object o is considered to spatially dominate another o if o is not worse than o for all search criteria and strictly better than o for at least one of the search criteria. Here, the search criteria include the objects' nearness to q and their non-spatial attributes. LDSQs have many valuable applications that need to find the best and nearest objects. Nevertheless, efficient evaluation of LDSQs faces challenges due to exhaustive comparisons among objects in determining their spatial dominance relationships which in turn depend on query points at the run time. In this paper, we introduce a notion of non-dominance scopes. For each object, a non-dominance scope is an area in which query points find the object not spatially dominated by other objects. With non-dominance scopes, LDSQs are simplified as searches for objects whose non-dominance scopes enclose query points. We develop algorithms to compute non-dominance scopes and evaluate LDSQs using indexed non-dominance scopes. We also evaluate our proposed approach. The experiment results show the outstanding performance of our proposed approach.

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Section: Related Workmentioning

confidence: 99%

Efficient evaluation of location-dependent skyline queries using non-dominance scopes

Lee

2011

Proceedings of the 2nd International Conference on Computing for Geospatial Research &Amp; Applications - COM.Geo '11

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“…The work proposed by [19] focus on the process of skyline queries in a database that is sorted in a Z-order (Zcurve). They argued that Z-order properties facilitated and improved the process of test dominance relationship among data items.…”

Section: Related Workmentioning

confidence: 99%

A Framework for Identifying Skylines over Incomplete Data

Alwan

Ibrahim

Udzir

2014

2014 3rd International Conference on Advanced Computer Science Applications and Technologies

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Skyline queries provide a flexible query operator that returns data items (skylines) which are not being dominated by other data items in all dimensions (attributes) of the database. Most of the existing skyline techniques determine the skylines by assuming that the values of dimensions for every data item are available (complete). However, this assumption is not always true particularly for multidimensional database as some values may be missing. The incompleteness of data leads to the loss of the transitivity property of skyline technique and results into failure in test dominance as some data items are incomparable to each other. Furthermore, incompleteness of data influences negatively on the process of finding skylines, leading to high overhead, due to exhaustive pairwise comparisons between the data items. This paper proposed a framework to process skyline queries for incomplete data with the aim of avoiding the issue of cyclic dominance in deriving skylines. The proposed framework for identifying skylines for incomplete data consists of four components, namely: Data Clustering Builder, Group Constructor and Local Skylines Identifier, k-dom Skyline Generator, and Incomplete Skylines Identifier. Including these processes in the proposed framework has optimized the process of identifying skylines in incomplete database by reducing the necessary number of pairwise comparison through eliminating the dominated data items as early as possible before applying the skyline technique.

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“…E.g., see [39] and Figure 2. Such curves are often used in spatial data indexing applications, e.g., see [4,[27][28][29][30]40], so as to reduce multi-dimensional approximate nearest-neighbor and range queries to 1-dimensional range queries. For example, each D i could be a collection of items along a 1-dimensional line or space-filling curve such that each D i is associated with a certain category, such as keyword matches for coffee shops or parking garages.…”

Section: Problem Formulationmentioning

confidence: 99%

Answering Spatial Multiple-Set Intersection Queries Using 2-3 Cuckoo Hash-Filters

Goodrich

2017

Proceedings of the 25th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems

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We show how to answer spatial multiple-set intersection queries in O(n(log w)/w + kt) expected time, where n is the total size of the t ≤ w c sets involved in the query, w is the number of bits in a memory word, k is the output size, and c ≥ 1 is any fixed constant. This improves the asymptotic performance over previous solutions and is based on an interesting data structure, known as 2-3 cuckoo hash-filters. Our results apply in the word-RAM model (or practical RAM model), which allows for constant-time bit-parallel operations, such as bitwise AND, OR, NOT, and MSB (most-significant 1-bit), as exist in modern CPUs and GPUs. Our solutions apply to any multiple-set intersection queries in spatial data sets that can be reduced to one-dimensional range queries, such as spatial join queries for one-dimensional points or sets of points stored along space-filling curves, which are used in GIS applications.

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Z-SKY: an efficient skyline query processing framework based on Z-order

Cited by 87 publications

References 22 publications

Efficient evaluation of location-dependent skyline queries using non-dominance scopes

Efficient evaluation of location-dependent skyline queries using non-dominance scopes

A Framework for Identifying Skylines over Incomplete Data

Answering Spatial Multiple-Set Intersection Queries Using 2-3 Cuckoo Hash-Filters

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