Data engineering·Moving data out of the source
the data was cleaned and reshaped by a job in the middle, and the warehouse only ever saw the tidy version.
ETL
Also calledextract transform load
Extract from the source, transform in a processing tier you run, then load the finished shape into the warehouse. It is the older arrangement and it exists because warehouse compute used to be the scarcest, most expensive thing in the building, so you did the work elsewhere. The cost shows up when someone asks a question the transform threw away the answer to: the raw rows are gone, and getting them back means a new pipeline and a wait.