DATABRICKS-DEA Question 100

Community Discussion

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• Chose A0

  - Correct answer : A — Salting the skewed key with a random suffix before grouping, then re-aggregating to spread its rows across partitions. A . This is correct. Salting appends a random suffix to the overrepresented key, splitting its rows across several synthetic sub-keys during the first aggregation pass, then a second pass aggregates the partial results back together, distributing the heavy key's workload across many tasks. B . Reducing the shuffle partition count consolidates data into fewer partitions, which would make the imbalance worse, not better, since the already-heavy key's partition would absorb even more of the remaining data. C . An aggregation is not a join between two tables, so there is no join side to broadcast; this option does not apply to reducing skew within a single `groupBy` on one DataFrame. D . Repartitioning by an unrelated surrogate column changes how rows are physically distributed for storage but does not affect how Spark shuffles data by the grouping key during the aggregation itself, so the skew on that key remains.