Type 2

Definition

Type 2 refers to a method of managing Slowly Changing Dimensions (SCD) in data warehousing where historical data is preserved by creating new records for each change in attribute values. This approach allows organizations to track and analyze changes over time, maintaining a complete history of an entity's attributes while keeping the current state intact. Type 2 is crucial for businesses that need to report on historical trends and analyze changes in their data, providing a comprehensive view of an entity’s evolution.

5 Must Know Facts For Your Next Test

1. Type 2 creates new records with new surrogate keys whenever an attribute changes, ensuring historical accuracy.
2. This method typically involves additional fields like 'Effective Date' and 'End Date' to manage the lifecycle of each record.
3. Using Type 2 can increase database size significantly because it maintains all historical records rather than overwriting them.
4. In Type 2 modeling, users can analyze trends over time, making it easier to understand the impact of changes in business dimensions.
5. Type 2 is often preferred in scenarios where audit trails or compliance with regulations necessitate detailed historical tracking.

Review Questions

• How does Type 2 differ from Type 1 in handling changes to dimensional data?
  • Type 2 differs from Type 1 primarily in how changes to dimensional data are managed. While Type 1 simply overwrites old attribute values, thereby losing any historical context, Type 2 preserves this history by creating new records with distinct surrogate keys. This allows organizations to retain a complete historical view of their dimensions, which is essential for comprehensive reporting and analysis over time.
• Discuss the importance of the Effective Date and End Date fields in a Type 2 implementation.
  • The Effective Date and End Date fields are crucial components of a Type 2 implementation as they help track the lifecycle of each record. The Effective Date marks when the record becomes valid, while the End Date indicates when it is no longer applicable. This dual date system allows users to determine the active record at any given point in time and facilitates accurate historical analysis by providing context for when changes occurred.
• Evaluate the implications of using Type 2 on database management and reporting capabilities within an organization.
  • Using Type 2 has significant implications for both database management and reporting capabilities. While it enhances the ability to perform historical analysis and track changes over time, it also increases the complexity of database management due to larger data volumes and additional metadata requirements. Organizations must ensure they have adequate storage and processing power to handle this increased load. However, the benefits in terms of informed decision-making and trend analysis can outweigh these challenges, making Type 2 a valuable strategy for businesses focused on understanding their evolving data landscape.

Related terms

Slowly Changing Dimensions (SCD): A concept in data warehousing that refers to dimensions that change slowly over time, requiring special handling to maintain historical accuracy.

Type 1: A method of handling Slowly Changing Dimensions where changes overwrite old data, losing the historical record of previous values.

Conformed Dimensions: Dimensions that are consistent and shared across multiple fact tables or data marts, allowing for integrated reporting and analysis.