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Extraction, Transformation, and Loading

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Encyclopedia of Database Systems

Synonyms

Data warehouse back stage; Data warehouse refreshment; ELT; ETL; ETL process; ETL tool

Definition

Extraction, transformation, and loading (ETL) processes are responsible for the operations taking place in the back stage of a data warehouse architecture. In a high-level description of an ETL process, first, the data are extracted from the source data stores that can be online transaction processing (OLTP) or legacy systems, files under any format, web pages, various kinds of documents (e.g., spreadsheets and text documents), or even data coming in a streaming fashion. Typically, only the data that are different from the previous execution of an ETL process (newly inserted, updated, and deleted information) should be extracted from the sources. After this phase, the extracted data are propagated to a special-purpose area of the warehouse, called the data staging area (DSA), where their transformation, homogenization, and cleansing take place. The most frequently used...

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Author information

Authors and Affiliations

  1. HP Labs, Palo Alto, CA, USA

    Alkis Simitsis

  2. University of Ioannina, Ioannina, Greece

    Panos Vassiliadis

Authors
  1. Alkis Simitsis
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  2. Panos Vassiliadis
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Corresponding author

Correspondence to Alkis Simitsis .

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, Aalborg University, Selma Lagerlöfs Vej 300, 9220, Aalborg, Denmark

    Torben Bach Pedersen

  2. DISI, University of Bologna, Viale Risorgimento, 2, 40136, Bologna, Italy

    Stefano Rizzi

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Simitsis, A., Vassiliadis, P. (2017). Extraction, Transformation, and Loading. In: Liu, L., Özsu, M. (eds) Encyclopedia of Database Systems. Springer, New York, NY. https://doi.org/10.1007/978-1-4899-7993-3_158-3

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  • DOI: https://doi.org/10.1007/978-1-4899-7993-3_158-3

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  • Print ISBN: 978-1-4899-7993-3

  • Online ISBN: 978-1-4899-7993-3

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