12. Data Hierarchies and Groups
12.1 What Is a Hierarchy?
A hierarchy (श्रेणीरचना) is an ordered set of columns from the same table, from general to detailed. Users can drill down from a higher level to a lower one (Module 16).
| Hierarchy | Levels | Example path |
|---|---|---|
| Date (Date table) | Year › Quarter › Month › Day | 2025 › Q4 › October › 20 |
| Location (DarkStore) | State › City › Area › Store Name | Maharashtra › Pune › Kothrud › Blinkit Kothrud Hub |
| Product (Product) | Category › Sub Category › Product Name | Fruits & Vegetables › Fresh Fruits › Nashik Grapes 500 g |
Simple bhashet sangaycha tar, levels must be in one table. That is one reason why dimension tables such as DarkStore contain State, City and Area together (star schema, Module 11).
Ravindra Bagale's Tip
Mitrano, khup students confuse a hierarchy with a group. A hierarchy is a drill path (State › City › Area › Store). A group combines values into buckets (Pune + Solapur = West). Use the right tool, and you can combine them, udaharan mhanje Region › City.