Databricks Certified Associate Developer for Apache Spark — Question 171

The code block shown below should return a new 4-partition DataFrame from the 8-partition DataFrame storesDF without inducing a shuffle. Choose the response that correctly fills in the numbered blanks within the code block to complete this task.

Code block:

_1_._2_(_3_)

Answer options

• A. 1. storesDF 2. coalesce 3. Nothing
• B. 1. storesDF 2. coalesce 3. 4
• C. 1. storesDF 2. coalesce 3. 4, "storeId"
• D. 1. storesDF 2. coalesce 3. "storeId"

Correct answer: B

Explanation

The correct answer is B because the coalesce function is used to reduce the number of partitions without triggering a shuffle, and specifying 4 as the argument will create a DataFrame with 4 partitions. Option A is incorrect because 'Nothing' is not a valid argument, while options C and D incorrectly include an additional parameter that is not needed for simply reducing the partition count.