Databricks Data Engineer Associate Question 405
Select 3You are implementing a Change Data Capture (CDC) pipeline using Databricks, and you are utilizing the APPLY CHANGES INTO command to process incremental updates into a target Delta table. The source table contains change records with the following columns: id, value, timestamp, and operation (with possible values 'insert', 'update', or 'delete'). Which of the following statements accurately describe the behavior of APPLY CHANGES INTO in this scenario?
- A
APPLY CHANGES INTOrequires a unique key column, such asid, to track changes and apply them correctly to the target table. - B
APPLY CHANGES INTOautomatically manages merging, including handling insert, update, and delete operations, based on theoperationcolumn in the source data. - C
When using
APPLY CHANGES INTO, the target Delta table schema must exactly match the schema of the source table. - D
APPLY CHANGES INTOprocesses only the latest change for each key within a single batch, ensuring idempotent updates to the target Delta table. - E
The
APPLY CHANGES INTOcommand does not support delete operations and will ignore any rows where theoperationcolumn is set to 'delete'.
Show answer and explanation
Correct answers: A, B, D
Explanation
APPLY CHANGES INTO is a Databricks-specific command for implementing Change Data Capture (CDC) patterns. It requires a unique key column to track changes, supports insert, update, and delete operations, and ensures idempotency by processing only the latest change for each unique key within a batch. This makes it highly efficient and reliable for managing incremental updates to Delta tables in a CDC pipeline.
- A. Correct.
Correct:
APPLY CHANGES INTOrequires a unique key column to identify rows in the target table and apply changes such as inserts, updates, or deletes correctly. - B. Correct.
Correct:
APPLY CHANGES INTOhandles all types of operations (insert, update, delete) automatically as long as the source data provides the necessary information (e.g., theoperationcolumn). - C. Incorrect.
Incorrect: The schema of the target Delta table does not have to exactly match the schema of the source table. However, the target must include the necessary columns for processing changes.
- D. Correct.
Correct:
APPLY CHANGES INTOensures idempotency by processing only the latest change for each unique key within a batch, avoiding duplicate or conflicting updates. - E. Incorrect.
Incorrect:
APPLY CHANGES INTOsupports delete operations and will apply them to the target table when specified in the source data.