Bottom-Up Approach

This approach starts by creating small, specific data marts for individual business units. These data marts are designed to meet the immediate analytical needs of departments. Over time, these marts are integrated into a comprehensive enterprise data warehouse (EDW). The bottom-up approach is agile and allows quick wins but can lead to challenges integrating data marts into a cohesive system.

External Sources (ETL)     >> Data Mart 1  >> Data Warehouse >> Data Mining
                           >> Data Mart 2

Kimball gives this approach: data marts are created first and provide a thin view for analysis, and a data warehouse is created after complete data marts have been created.