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Contribution Details

Type Journal Article
Scope Discipline-based scholarship
Title Category- and selection-enabled nearest neighbor joins
Organization Unit
Authors
  • Francesco Cafagna
  • Michael Hanspeter Böhlen
  • Annelies Bracher
Item Subtype Original Work
Refereed Yes
Status Published in final form
Language
  • English
Journal Title Information Systems
Publisher Elsevier
Geographical Reach international
ISSN 0306-4379
Volume 68
Page Range 3 - 16
Date 2017
Abstract Text This paper proposes a category- and selection-enabled nearest neighbor join (NNJ) between relation r and relation s, with similarity on T and support for category attributes C and selection predicate θ. Our solution does not suffer from redundant fetches and index false hits, which are the main performance bottlenecks of current nearest neighbor join techniques. A category-enabled NNJ leverages the category attributes C for query evaluation. For example, the categories of relation r can be used to limit relation s accessed at most once. Solutions that are not category-enabled must process each category independently and end up fetching, either from disk or memory, the blocks of the input relations multiple times. A selection-enabled NNJ performs well independent of whether the DBMS optimizer pushes the selection down or evaluates it on the fly. In contrast, index-based solutions suffer from many index false hits or end up in an expensive nested loop. Our solution does not constrain the physical design, and is efficient for row- as well as column-stores. Current solutions for column-stores use late materialization, which is only efficient if the data is clustered on the category attributes C. Our evaluation algorithm finds, for each outer tuple r, the inner tuples that satisfy the equality on the category and have the smallest distance to r with only one scan of both inputs. We experimentally evaluate our solution using a data warehouse that manages analyses of animal feeds.
Digital Object Identifier 10.1016/j.is.2017.01.006
Other Identification Number merlin-id:15013
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