Databricks Data Engineer Professional Question 190
Select 3You are tasked with implementing a Slowly Changing Dimension (SCD) Type 2 table in Delta Lake. The table is updated using both streaming and batch workloads. Which of the following steps are necessary to ensure accurate SCD Type 2 behavior?
- A
Use the MERGE INTO statement to handle both insertions and updates in Delta Lake.
- B
Ensure that every record has a unique surrogate key to identify distinct dimension rows.
- C
Use Delta Lake's
ZORDERoptimization to manage changes in the dimension table. - D
Maintain historical versions of records by inserting new rows with updated effective dates and marking old rows as inactive.
- E
Configure Delta Lake's schema evolution to automatically handle changes in the structure of the incoming data.
Show answer and explanation
Correct answers: A, B, D
Explanation
SCD Type 2 tables are designed to track historical changes in dimension data. Delta Lake's MERGE INTO statement is crucial for implementing the logic to either update existing rows or insert new rows. A unique surrogate key ensures proper identification of each version of a record, while maintaining historical versions requires inserting new rows and marking old ones as inactive. Features like ZORDER and schema evolution, while useful for other use cases, do not directly contribute to the SCD Type 2 implementation.
- A. Correct.
Correct: The MERGE INTO statement is a key feature in Delta Lake for handling complex operations like SCD Type 2, as it allows conditional updates and inserts.
- B. Correct.
Correct: A unique surrogate key is essential for tracking and differentiating multiple versions of a dimension record over time.
- C. Incorrect.
Incorrect: While
ZORDERimproves query performance, it is not directly relevant to implementing SCD Type 2 logic or maintaining historical data. - D. Correct.
Correct: SCD Type 2 requires maintaining historical versions of records, typically achieved by marking old rows as inactive and inserting new rows with updated effective and expiration dates.
- E. Incorrect.
Incorrect: While schema evolution can handle changes in incoming data structure, it does not address the logic required for managing SCD Type 2 updates.