Encyclopedia of Database Systems

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

Extraction, Transformation, and Loading

  • Alkis Simitsis
  • Panos Vassiliadis
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_158

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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Copyright information

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

Authors and Affiliations

  1. 1.HP LabsPalo AltoUSA
  2. 2.University of IoanninaIoanninaGreece