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Extract, Load, Transform (ELT) is a method of data extraction where modifications to the data, such as transformations, take place after the loading process. The storage and scaling capabilities of modern cloud data warehouses enable data to be moved in its entirety and then modified after the fact. ELT transformations enable you to rename columns, change data values by applying SQL functions, and map them to destination columns. You can also add new values that are computed directly within the data pipeline.

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Differences between ELT and ETL

Traditionally, ETL (Extract, Transform, Load) has been the most popular way to move and transform data. However, with the rise of cloud computing and the greatly expanded storage capacity of databases, ELT is gradually overtaking ETL as the preferred method of data delivery and transformation. The primary difference between the ELT and ETL is the order in which the steps take place. However, ELT also has other benefits:
  • Performance: The larger storage limits of modern databases enable ELT to move the entirety of updated data before implementing changes. Because the data does not need to be cleaned or modified ahead of time, the speed and efficiency of the transformation is greatly increased when compared to traditional ETL methods.
  • Simplicity: In situations where you need to move a large amount of data, ELT streamlines and simplifies the transformation process.

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The Transformations Page

To open the Transformations page, click Transformations in the side navigation bar of the application. From this page, you can perform the following tasks:
  • Add new transformations.
  • View a list of previously configured transformations.
  • Edit and delete transformations.
  • Run transformations.
You can create and run two types of transformations:
  • SQL transformations
  • dbt Core transformations
For details about these transformations, see SQL Transformations and DBT Transformations.