extract, transform, load (ETL)

This definition is part of our Essential Guide: An admin's guide to AWS data management

In managing databases, extract, transform, load (ETL) refers to three separate functions combined into a single programming tool. First, the extract function reads data from a specified source database and extracts a desired subset of data. Next, the transform function works with the acquired data - using rules or lookup tables, or creating combinations with other data - to convert it to the desired state. Finally, the load function is used to write the resulting data (either all of the subset or just the changes) to a target database, which may or may not previously exist.

ETL can be used to acquire a temporary subset of data for reports or other purposes, or a more permanent data set may be acquired for other purposes such as: the population of a data mart or data warehouse; conversion from one database type to another; and the migration of data from one database or platform to another.

ETL can be contrasted with ELT (Extract, Load, Transform)  which transfers raw data from a source server to a data warehouse on a target server and then prepares the information for downstream uses. 

compare ETL with ELT

This was last updated in November 2005

Continue Reading About extract, transform, load (ETL)

Start the conversation

Send me notifications when other members comment.

Please create a username to comment.


File Extensions and File Formats

Powered by: