AI engineering glossary · Data engineering
What is SCD (slowly changing dimension)?
Slowly changing dimension (also called SCD): A technique for handling descriptive attributes that change infrequently, such as a customer's city. Type 1 overwrites the old value, while Type 2 adds a new row with validity dates so history is preserved.
Slowly changing dimension: an example
When a customer moves from Chennai to Bengaluru, a Type 2 approach keeps both rows with start and end dates so old sales remain tied to Chennai.
Related terms
More Data engineering terms
- Small files problem
- Snowflake
- Snowflake schema
- Star schema
- Stream processing
- Surrogate key
- Time travel
- Topic
Where you learn it
Slowly changing dimension is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.