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Discuss a project where you significantly impacted performance or cost optimization.

SQLhard0.4 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
EPAM
Key Concepts Tested
bigqueryoptimizationpartition
Expert AnswerPremium
76 wordsInterview-ready
**Situation**: BigQuery costs spiked 40% MoM from ad-hoc queries. **Task**: Reduce cost without blocking users. **Action**: (1) Identified heavy users and expensive queries. (2) Implemented partitioned tables and clustering. (3) Created materialized views for common patterns. (4) Added query cost alerts. (5) Trained users on partition pruning. Also: optimized 2-hour nightly job to 15 min via incremental. **Result**: 35% cost reduction; faster queries....
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 EPAM. The answer also includes follow-up discussion points that interviewers commonly explore.

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