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repartition() vs coalesce(): Explain when to use repartition() (increases partitions) vs coalesce() (reduces partitions).

SQLmedium0.3 min readPremium
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Asked at 1 company
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487
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1,863
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Asked at these companies
Capgemini
Key Concepts Tested
partition
Expert AnswerPremium
54 wordsInterview-ready
**repartition(n)**: Full shuffle; increase or decrease partitions. Use when needing more parallelism or redistribute after skew. **coalesce(n)**: Reduces without full shuffle; merges adjacent. Use when reducing before write (e.g., fewer files). **Scalability**: repartition expensive; coalesce cheaper for reduction. **Cost**: coalesce(1) = single-partition bottleneck on large data—avoid....
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