Encyclopedia of GIS

2008 Edition
| Editors: Shashi Shekhar, Hui Xiong

Top-k OLAP Queries Using Augmented Spatial Access Methods

  • Nikos Mamoulis
  • Spiridon Bakiras
  • Panos Kalnis
Reference work entry
DOI: https://doi.org/10.1007/978-0-387-35973-1_1391

Synonyms

Top-k OLAP queries using multi-resolution tree structures; OLAP query; Top-k query

Definition

A top-k OLAP query groups measurements with respect to some abstraction level of interesting dimensions and selects the k groups with the highest aggregate value. An example of such a query is “find the 10 combinations of product-type and month with the largest sum of sales”. Top‑k queries may also be applied in a spatial database context, where objects are augmented with some measures that must be aggregated according to a spatial division. For instance, consider a map of objects (e. g., restaurants) where each object carries some non-spatial measure (e. g., the number of customers served during the last month). Given a partitioning of the space into regions (e. g., city districts), the goal is to find the regions with the highest number of served customers. Formally, the top-k OLAP query can be defined as follows:

Let\( \mathcal{D} = \{d_1,\dots,d_m\} \)

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Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Nikos Mamoulis
    • 1
  • Spiridon Bakiras
    • 1
  • Panos Kalnis
    • 2
  1. 1.Department of Computer ScienceUniversity of Hong KongHong KongChina
  2. 2.Department of Computer ScienceNational University of SingaporeSingaporeSingapore