Data Warehouse — Slowly Changing Dimensions (SCDs)

Slowly Changing Dimensions (SCDs) are a concept in data warehousing used to manage and track changes in dimension data over time. Dimension tables typically contain descriptive attributes related to the facts in a data warehouse, such as customer or product information. However, these attributes can change over time, and different strategies are required to handle these changes while maintaining historical accuracy and data integrity.

A Slowly Changing Dimension (SCD) is a dimension that stores and manages both current and historical data over time in a data warehouse. It is considered and implemented as one of the most critical ETL tasks in tracking the history of dimension records. Here are some examples of SCDs:
* Customer dimension: Attributes like name, address, phone number, age, gender, and location
* Product dimension: Attributes like price, category, specifications, and descriptions
* Employee dimension: Attributes like job title, department, and salary

🔍Real-life example: Monitoring changes in customer loyalty levels (e.g., Silver to Gold). A new column stores the prior loyalty level while the current level is updated.

🚀 Types of Slowly Changing Dimensions (SCDs) — There are several types of SCDs, each with different approaches to handling changes:

• 📌SCD Type 0 (Fixed…