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Type Journal Article
Scope Discipline-based scholarship
Title theta-Constrained multi-dimensional aggregation
Organization Unit
Authors
  • Michael Akinde
  • Michael Hanspeter Böhlen
  • Damianos Chatziantoniou
  • Johann Gamper
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 (P) 1873-6076 (E)
Volume 36
Number 2
Page Range 341 - 358
Date 2011
Abstract Text The SQL:2003 standard introduced window functions to enhance the analytical processing capabilities of SQL. The key concept of window functions is to sort the input relation and to compute the aggregate results during a scan of the sorted relation. For multi-dimensional OLAP queries with aggregation groups defined by a general θ condition an appropriate ordering does not exist, though, and hence expensive join-based solutions are required.In this paper we introduce θ-constrained multi-dimensional aggregation (θ-MDA), which supports multi-dimensional OLAP queries with aggregation groups defined by inequalities. θ-MDA is not based on an ordering of the data relation. Instead, the tuples that shall be considered for computing an aggregate value can be determined by a general θ condition. This facilitates the formulation of complex queries, such as multi-dimensional cumulative aggregates, which are difficult to express in SQL because no appropriate ordering exists. We present algebraic transformation rules that demonstrate how the θ-MDA interacts with other operators of a multi-set algebra. Various techniques for achieving an efficient evaluation of the θ-MDA are investigated, and we integrate them into concrete evaluation algorithms and provide cost formulas. An empirical evaluation with data from the TPC-H benchmark confirms the scalability of the θ-MDA operator and shows performance improvements of up to one order of magnitude over equivalent SQL implementations.Keywords: OLAP; SQL/OLAP; Window functions; Multi-dimensional aggregation
Digital Object Identifier 10.1016/j.is.2010.07.005
Other Identification Number merlin-id:2494
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