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Describe strategies for optimizing a slow-running query on a massive dataset.

SQLmedium0.4 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
BCG
Key Concepts Tested
partition
Expert AnswerPremium
81 wordsInterview-ready
**Architectural Logic**: Optimize in order—partition pruning, clustering, query rewrite, materialization, approximate methods. **Strategies**: (1) Partition pruning—predicate on partition column. (2) Clustering/sort keys—colocate related data. (3) Query rewrite—avoid SELECT *; push filters; reduce shuffle. (4) Materialized views—pre-aggregate common patterns. (5) Approximate—sampling, HyperLogLog when exact not needed. (6) Incremental—process only changed data....
The complete answer continues with detailed implementation patterns, architectural trade-offs, and production-grade considerations. It covers performance optimization strategies, common pitfalls to avoid, and real-world examples from companies like BCG. The answer also includes follow-up discussion points that interviewers commonly explore.

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