Encyclopedia of Database Systems

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

Evaluation of Relational Operators

Living reference work entry
DOI: https://doi.org/10.1007/978-1-4899-7993-3_154-2



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

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    Graefe G. Query evaluation techniques for large databases. ACM Comput Surv. 1993;25(2):73–170.CrossRefGoogle Scholar
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    Mishra P, Eich MH. Join processing in relational databases. ACM Comput Surv. 1992;24(1):63–113.CrossRefGoogle Scholar
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    Ramakrishnan R, Gehrke J. Database management systems. New York: McGraw-Hill; 2002.MATHGoogle Scholar
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    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.Google Scholar

Copyright information

© Springer Science+Business Media LLC 2017

Authors and Affiliations

  1. 1.Alibaba GroupHangzhouChina

Section editors and affiliations

  • Evaggelia Pitoura
    • 1
  1. 1.Department of Computer Science and EngineeringUniversity of IoanninaIoanninaGreece