SCD - Type 0

Type 0 - Retain Original: This approach ignores changes and retains the original values for the dimension attributes. No history is kept for changes.

The Product dimension table might include the following columns:

1. Product_ID

2. Product_Name

3. Category

4. Price

Now, imagine that the store decides to re-categorize one of its products. For instance, they may change the "Smartphone" product from the "Electronics" category to the "Mobile Devices" category.

Using a Type 0 Slowly Changing Dimension approach, the store will retain the original value for the product category, ignoring the change. In this case, the Product dimension table would still show the "Smartphone" product in the "Electronics" category, even though it has been re-categorized to "Mobile Devices." This approach means no history is kept for changes, and the original values are always preserved.

The Product dimension table would look like this:

Product_ID	Product_Name	Category	Price
1	Smartphone	Electronics	1000

Use Cases:

1. When historical data is not relevant or necessary for analysis, and only the original values are needed.

2. For dimensions with attributes that are fixed and don't change over time, such as unique identifiers or codes.

3. In cases where the data warehouse is only required to support reporting and analysis on the current state of the business and not the historical trends.

Advantages:

1. Simplicity: SCD Type 0 is the simplest approach, as it doesn't require any additional mechanisms to handle changes in dimension attributes.

2. Space Efficiency: Since there is no need to store historical data or multiple versions of records, the dimension tables will be smaller and require less storage space.

3. Performance: As there are no additional rows or columns for historical data, the querying and processing of the data warehouse will generally be faster.

Disadvantages:

1. Lack of Historical Data: SCD Type 0 does not store any historical data, which means it cannot support reporting and analysis that requires tracking changes over time. This can be a significant limitation for businesses that need to analyze trends, understand the impact of changes, or perform other historical analyses.

2. Inaccurate Analysis: Since the dimension table only contains the original values, any changes that have occurred over time are not reflected. This may lead to incorrect analysis results or conclusions based on outdated information.

3. Inability to Track Changes: With SCD Type 0, it is impossible to determine when or why changes occurred, as there is no record of any changes in the dimension data.