Databricks Data Engineer Associate Question 401
Select 2A data engineer is configuring a Delta table to enforce a NOT NULL constraint on the 'customer_id' column. The engineer wants to understand the impact of using ON VIOLATION DROP ROW versus ON VIOLATION FAIL UPDATE during an insert operation where some rows violate the constraint. What will happen if the constraint is violated?
- A
The rows violating the NOT NULL constraint will be excluded from the table with ON VIOLATION DROP ROW.
- B
The entire operation will fail if any row violates the constraint when using ON VIOLATION FAIL UPDATE.
- C
The violating rows will be inserted into the table with a warning when using ON VIOLATION DROP ROW.
- D
The entire table will be dropped if ON VIOLATION FAIL UPDATE is used and a constraint violation occurs.
Show answer and explanation
Correct answers: A, B
Explanation
The ON VIOLATION DROP ROW and ON VIOLATION FAIL UPDATE options define how Delta Lake handles constraint violations during write operations. DROP ROW removes invalid rows from the operation, allowing the rest to succeed, while FAIL UPDATE halts the entire operation if any constraint is violated. Understanding these behaviors is critical for ensuring data integrity and managing errors effectively in Delta tables.
- A. Correct.
This is correct because ON VIOLATION DROP ROW excludes rows that violate constraints during the write operation, ensuring only valid rows are inserted.
- B. Correct.
This is correct because ON VIOLATION FAIL UPDATE stops the entire transaction if any row violates the defined constraints.
- C. Incorrect.
This is incorrect because ON VIOLATION DROP ROW removes violating rows from the operation, not inserts them into the table.
- D. Incorrect.
This is incorrect because ON VIOLATION FAIL UPDATE does not drop the entire table, it only fails the specific write or update operation.