What is Extract/Transform/Load (ETL)?

Question

I've tried reading the Wikipedia article for "extract, transform, load", but that just leaves me more confused...

Can someone explain what ETL is, and how it is actually done?

Answer 1

ETL is taking data from one system (extract), modifying it (transform) and loading it into another system (load).

And not necessarily in that order. You can TEL, or ELT. Probably not LTE though. :-)

It's a catch-all name for any process that takes data from one system and moves it to another.

Answer 2

ETL is commonly used for data warehousing. It's not a specific implementation to load a data warehouse, it's just a very high-level algorithm that should be used to populate a data warehouse.

• Extract pulls data from some source.
• Transform takes the data and manipulates it so that it can be used for..
• Loading into your system.