The first layer in traditional data warehousing and business intelligence is the data source or data integration layer. This layer is responsible for collecting and extracting data from various source systems such as operational databases, front-end applications, CRM, and ERP systems. It represents the starting point where raw data is gathered before any transformation or loading occurs. Extraction is the first phase of ETL (Extract, Transform, Load) or ELT (Extract, Load, Transform) processes, which prepare the data for further processing in the warehouse
. In summary, the first layer is:
- Data Source Layer : Where data is extracted from multiple operational and external sources, serving as the raw input for the data warehouse system
