Kimball builds the warehouse bottom up, one business process at a time, each as a star. What turns separate stars into one warehouse is conformed dimensions: a dimension built once and shared, with the same keys and attribute values, by every fact table that uses it. Sales and returns then group by the same dim_book and their results line up row for row. The plan is the bus matrix: business processes as rows, dimensions as columns, and a mark wherever a process uses a dimension.
| Business process | Date | Book | Customer | Order profile | Warehouse |
|---|---|---|---|---|---|
| Orders (fact_sales) | x | x | x | x | |
| Returns | x | x | x | x | x |
| Inventory snapshot | x | x | x | ||
| App events (page views) | x | x | x |
Read a column to see which processes a dimension must serve, and a row to scope the next star. The approach delivers value early, one process at a time, but it relies on the discipline of conforming: two teams that each build their own customer dimension produce two answers to the same question.