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How would you deal with data skewness in a join operation?

SQLmedium0.3 min readPremium
Frequency
Low
Asked at 1 company
Category
487
questions in SQL
Difficulty Split
130E|271M|86H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Capgemini
Key Concepts Tested
joinspark
Expert AnswerPremium
52 wordsInterview-ready
**Identify**: Skewed keys (e.g., NULL, bot user_id). **Solutions**: (1) **Salting**: Add random suffix 0..N to key in both tables; join; aggregate. (2) **Broadcast**: If one side small. (3) **Skew join**: Process skewed keys separately. (4) **AQE**: Spark 3.x auto-optimizes. **Trade-off**: Salting adds shuffle; AQE is automatic....
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