Degenerate Dimension

Generally, what is a Dimension table? Something like a master list. Employee, Product, Date, Store.

In a data warehouse, a degenerate dimension is a dimension key in the fact table that does not have its dimension table.

It is key in the fact table but does not have its dimension table.

Degenerate dimensions are most familiar with the transaction and accumulating snapshot fact tables.

Means no separate Dimension table.

OrderNo is degenerate dimension. As it has no Dimension table.

Uses of using Degenerate Dimension Table

- Grouping line items
- Getting the average sale
- Tracking

Other Examples of Degenerate Dimensions are

1. Order number or invoice number: This is a typical example of a degenerate dimension. It is a unique identifier for an order or an invoice but has no meaningful attributes other than its value. This degenerate dimension can be used in a fact table to analyze sales by order or invoice number.

2. Tracking number: Another example of a degenerate dimension is a tracking number for a shipment. Like an order number, it is a unique identifier but has no additional attributes associated with it. It can be used in a fact table to analyze shipping performance or delivery times.

3. ATM transaction number: In banking, an ATM transaction number is a unique identifier for a transaction at an ATM. It can be used in a fact table to analyze ATM usage patterns and trends.

4. Serial number: A serial number is a unique identifier assigned to a product or equipment. It can be used in a fact table to analyze the performance of a particular product or equipment.

5. Coupon code: A coupon code is a unique identifier to redeem a discount or promotion. It can be used in a fact table to analyze the usage and effectiveness of different marketing campaigns or promotions.

Degenerate dimensions are helpful when we have a unique identifier for an event or transaction. Still, it has no additional attributes that make it sound like a separate dimension table. In these cases, we can include the unique identifier in the fact table as a degenerate dimension.