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Evaluation of Relational Operators

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Encyclopedia of Database Systems

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Synonyms

Implementation of database operators (joins, group by, etc.); Query evaluation; Query processing

Definition

A query usually consists of several relational operators. The corresponding physical query plan is composed of several physical operators. Generally speaking, a physical operator is an implementation of a relational operator. For each relational operator, there are several alternative algorithms (physical operators) for its implementation, and there is no universally superior one. So choosing physical operators wisely is crucial for query performance. Which physical operator is the best depends on several factors, such as the sizes of the input relations, the existing sorting orders of the input relations, the existing indexes/materialized views, the buffer replacement policy, the size of the available buffer pool, etc.

Historical Background

The relational operators serve as the building blocks for query processing. Their implementation techniques have been extensively...

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Recommended Reading

  1. Graefe G. Query evaluation techniques for large databases. ACM Comput Surv. 1993;25(2):73–170.

    Article  Google Scholar 

  2. Mishra P, Eich MH. Join processing in relational databases. ACM Comput Surv. 1992;24(1):63–113.

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  3. Ramakrishnan R, Gehrke J. Database management systems. New York: McGraw-Hill; 2002.

    MATH  Google Scholar 

  4. Selinger P.G., Astrahan M.M., Chamberlin D.D., Lorie R.A., and Price T.G. Access path selection in a relational database management system. In Proceedings of ACM SIGMOD International Conference on Management of Data; 1979. p. 23–34.

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Author information

Authors and Affiliations

  1. Alibaba Group, Hangzhou, China

    Jingren Zhou

Authors
  1. Jingren Zhou
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Corresponding author

Correspondence to Jingren Zhou .

Editor information

Editors and Affiliations

  1. Georgia Institute of Technology College of Computing, Atlanta, Georgia, USA

    Ling Liu

  2. University of Waterloo School of Computer Science, Waterloo, Ontario, Canada

    M. Tamer Özsu

Section Editor information

  1. Department of Computer Science and Engineering, University of Ioannina, P.O. Box 1186, 45110, Ioannina, Greece

    Evaggelia Pitoura

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Zhou, J. (2017). Evaluation of Relational Operators. In: Liu, L., Özsu, M. (eds) Encyclopedia of Database Systems. Springer, New York, NY. https://doi.org/10.1007/978-1-4899-7993-3_154-2

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  • DOI: https://doi.org/10.1007/978-1-4899-7993-3_154-2

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  • Publisher Name: Springer, New York, NY

  • Print ISBN: 978-1-4899-7993-3

  • Online ISBN: 978-1-4899-7993-3

  • eBook Packages: Springer Reference Computer SciencesReference Module Computer Science and Engineering

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