Encyclopedia of Database Systems

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

Access Path

  • Evaggelia PitouraEmail author
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_866


Access methods; Access path


An access path specifies the path chosen by a database management system to retrieve the requested tuples from a relation. An access path may be either (i) a sequential scan of the data file or (ii) an index scan with a matching selection condition when there are indexes that match the selection conditions in the query. In general, an index matches a selection condition, if the index can be used to retrieve all tuples that satisfy the condition.

Key Points

Access paths are the alternative ways for retrieving specific tuples from a relation. Typically, there is more than one way to retrieve tuples because of the availability of indexes and the potential presence of conditions specified in the query for selecting the tuples. Typical access methods include sequential access of unordered data files (heaps) as well as various kinds of indexes. All commercial database systems implement heaps and B+ tree indexes. Most of them also support hash...

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Recommended Reading

  1. 1.
    Selinger PG, Astrahan MM, Chamberlin DD, Lorie RA, Price TG. Access path selection in a relational database management system. In: Proceedings of the ACM SIGMOD International Conference on Management of Data; 1979. p. 23–34.Google Scholar

Copyright information

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

Authors and Affiliations

  1. 1.Department of Computer Science and EngineeringUniversity of IoanninaIoanninaGreece

Section editors and affiliations

  • Evaggelia Pitoura
    • 1
  1. 1.Dept. of Computer ScienceUniv. of IoanninaIoanninaGreece