Encyclopedia of Database Systems

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

Operator-Level Parallelism

  • Nikos HardavellasEmail author
  • Ippokratis Pandis
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_661


Inter-operator parallelism


Operator-level parallelism (or inter-operator parallelism) is a form of intra-query parallelism obtained by executing concurrently several operators of the same query. By contrast, intra-operator parallelism is obtained by executing the same operator on multiple processors, with each instance working on a different subset of data.

Historical Background

Parallelism has been a key focus of database research since the 1970s. For example, as early as 1978 Teradata was building highly-parallel database systems and quietly pioneered many of the ideas on parallel query execution [5]. However, the intra-query parallelism employed by these early systems was mostly intra-operator or independent parallelism (see Classes of Parallelism below). Gamma [4] was one of the first database systems that allowed operator-level parallelism through pipelining.


Parallel processing uses multiple processors cooperatively to improve the performance of...

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Copyright information

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

Authors and Affiliations

  1. 1.Carnegie Mellon UniversityPittsburghUSA
  2. 2.Amazon Web ServicesSeattleUSA

Section editors and affiliations

  • Anastasia Ailamaki
    • 1
  1. 1.Informatique et CommunicationsEcole Polytechnique Fédérale de LausanneLausanneSwitzerland