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How does AQE optimize join operations dynamically?

SQLhard0.3 min readPremium
Frequency
Low
Asked at 1 company
Category
487
questions in SQL
Difficulty Split
130E|271M|86H
in this category
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1,863
across 7 categories
Asked at these companies
PWC
Key Concepts Tested
joinoptimizationpartitionsparksql
Expert AnswerPremium
58 wordsInterview-ready
**Adaptive Query Execution** (Spark 3.x): Optimizes at runtime using actual statistics. **Join optimizations**: (1) Coalesce partitions after shuffle—merge small partitions. (2) Convert sort-merge to broadcast when runtime shows one side small. (3) Skew join—split large partition, replicate small side. **Enable**: spark.sql.adaptive.enabled=true. **Why**: Planner uses estimates; AQE corrects with real data....
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