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How do partitions improve query performance in fact tables?

SQLmedium0.3 min readPremium
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Asked at 1 company
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487
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1,863
across 7 categories
Asked at these companies
Microsoft
Key Concepts Tested
partition
Expert AnswerPremium
56 wordsInterview-ready
**Partition pruning**: Filter on partition column (e.g., dt) skips entire partition files—query reads only matching segments. **Scalability**: 1B rows partitioned by month = 12 segments; unpartitioned = full scan. **Columnar + partition**: Both reduce I/O; partition first (coarse), then columnar (fine). **Trade-off**: Low-cardinality partition (e.g., boolean) = few files, little pruning....
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