Encyclopedia of Database Systems

2018 Edition
| Editors: Ling Liu, M. Tamer Özsu

Approximate Query Processing

  • Qing Liu
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_534

Synonyms

Approximate query answering

Definition

Query processing in a database context is the process that deduces information that is available in the database. Due to the huge amount of data available, one of the main issues of query processing is how to process queries efficiently. In many cases, it is impossible or too expensive for users to get exact answers in the short query response time. Approximate query processing (AQP) is an alternative way that returns approximate answer using information which is similar to the one from which the query would be answered. It is designed primarily for aggregate queries such as count, sum and avg, etc. Given a SQL aggregate query Q, the accurate answer is y while the approximate answer is y′. The relative error of query Q can be quantified as:
$$ Error(Q)=\mid \frac{y-{y}^{\prime }}{y}\mid. $$
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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.CSIROHobartAustralia

Section editors and affiliations

  • Xiaofang Zhou
    • 1
  1. 1.School of Information Technology and Electrical EngineeringUniversity of QueenslandBrisbaneAustralia