HomeInterview QuestionsCan coalesce increase the number of partitions?

Can coalesce increase the number of partitions?

🟢 Easy Conceptual Fresher level
1Times asked
Jul 2026Last seen
Jul 2026First seen

💡 Model Answer

No. The coalesce transformation in Spark is designed to reduce the number of partitions by collapsing adjacent partitions without performing a full shuffle. It is efficient for shrinking the partition count, for example when you want to reduce the number of output files. If you need to increase the number of partitions, you should use repartition, which performs a shuffle to redistribute data across the new partitions.

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