Extract, load, transform
ELT is an alternative to Extract, transform, load (ETL) used with data lake implementations. In ELT models the data is not processed on entry to the data lake which enables faster loading times. But does require sufficient processing within the data processing engine to carry out the transform on demand and return the results to the consumer in a timely manner. Since the data is not processed on entry to the data lake the query and schema do not need to be defined a-priori (often the schema will be available during load since many data sources are extracts from databases or similar structured data systems and hence have an associated schema).
External links
- Davenport, Robert J., "ETL vs ELT: A Subjective View", www.dataacademy.com, June 2008. "Part of the series of the Insource Commercial Aspects of BI discussion papers."
- Dull, Tamara, "The Data Lake Debate: Pro is Up First", smartdatacollective.com, March 20, 2015.
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