Databricks Data Engineer Associate Question 400
Single answerYou are a data engineer managing a Delta table with a primary key constraint. During an upsert operation using the MERGE INTO statement, some rows violate the primary key constraint. You want to ensure that the operation continues by excluding only the violating rows while successfully writing the rest of the data. Which clause should you use to handle this scenario?
- A
ON VIOLATION FAIL UPDATE
- B
ON VIOLATION DROP ROW
- C
ON VIOLATION FAIL INSERT
- D
ON VIOLATION IGNORE ROW
Show answer and explanation
Correct answer: B
Explanation
The ON VIOLATION DROP ROW clause ensures that only the rows violating constraints are excluded while allowing the remaining data to be processed successfully. This is the desired behavior in the scenario described, making it the correct choice. Other clauses either stop the entire operation or are not applicable to this context.
- A. Incorrect.
This clause stops the entire operation if any constraint violation occurs. It is not suitable when you want to exclude only the violating rows and allow the rest of the data to be written.
- B. Correct.
This clause drops only the rows that violate the constraint and allows the rest of the data to be successfully written. This behavior matches the requirement in the scenario.
- C. Incorrect.
This clause applies to insert operations rather than upserts. It stops the operation for violating rows but does not match the behavior required in the scenario.
- D. Incorrect.
This clause does not exist in the context of Delta Lake or constraint handling. It is invalid.