Encyclopedia of Database Systems

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

Intra-query Parallelism

Living reference work entry
DOI: https://doi.org/10.1007/978-1-4899-7993-3_1557-2

Synonyms

Definition

Intra-query parallelism is a form of parallelism in the evaluation of database queries, in which a single query is decomposed into smaller tasks that execute concurrently on multiple processors.

Key Points

Intra-query parallelism is achieved when several processors cooperate in the execution of a single query to improve the query’;s response time. Intra-query parallelism is orthogonal to inter-query parallelism, in which multiple independent requests execute concurrently on several processors to improve the overall system throughput.

There exist two forms of intra-query parallelism: operator-level parallelism and intra-operator parallelism. Operator-level parallelism is obtained by executing concurrently several operators of the same query. For example, consider a simple query that consists of a scan operator and an aggregation. The scan operator uses a selection condition to filter tuples. The aggregation calculates some statistics over all...

This is a preview of subscription content, log in to check access

Recommended Reading

  1. 1.
    DeWitt DJ, Gray J. Parallel database systems: the future of high-performance database computing. Commun ACM. 1992;35(6):85–98.CrossRefGoogle Scholar
  2. 2.
    Graefe G.. Encapsulation of parallelism in the volcano query processing system. In: Proceeding of the ACM SIGMOD international conference on management of data; 1990, p. 102–11.Google Scholar

Copyright information

© Springer Science+Business Media LLC 2016

Authors and Affiliations

  1. 1.Carnegie Mellon UniversityPittsburghUSA