ETL Process

ETL is an acronym for a three step process to extract data from source systems and load the data to a data warehouse. The three steps of the ETL process are:

1. Extract and load Staging Tables: Extracts and consolidates data from one or more source systems and loads into the data warehouse staging tables.
   
2. Transforms the data: Transforms data in the staging tables and computes calculated values in preparation for the load.
   
3. Load Dimension and Fact Tables: Generates and maintains data warehouse surrogate keys and loads target dimension and fact tables.
   

ETL processes are further refined to two types of mappings:

1. Source Dependent Extract (SDE) mappings – extracts the data from the transactional systems and loads to the data warehouse staging tables. SDE mappings are designed with respect to the source’s unique data model.

Source System Databases

2. Source Independent Load (SIL) mappings – extracts and transforms data from the staging tables and loads to the data warehouse target tables. SIL mappings are designed to be universal with any source.