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Describe a scenario where you had to optimize a slow-running data pipeline.

System Design/Architecturemedium0.2 min read

**STAR**: **Situation**: Nightly job took 6 hr; SLA 2 hr. **Task**: Optimize. **Action**: Profiled—found full scan and skew. Partition pruning; broadcast join for dimension; salting for skew. **Result**: 1.5 hr; 4x improvement....

🤖 Analyze Your Answer
Frequency
Low
Asked at 1 company
Category
179
questions in System Design/Architecture
Difficulty Split
15E|6M|158H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Swiggy
Interview Pro Tip

Pro-Move: 'Spark UI showed 1 partition at 4hr—salted the key, added pruning; 6hr to 90min; documented in runbook.' Red Flag: We added more resources—optimization, not scaling.

Key Concepts Tested
joinpartition

Why This Question Matters

This medium-level System Design/Architecture question appears frequently in data engineering interviews at companies like Swiggy. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (join, partition) will help you answer variations of this question confidently.

How to Approach This

Break this problem into components. Identify the core trade-offs involved, then walk the interviewer through your reasoning step by step. Demonstrate awareness of edge cases and production considerations - this is what separates good answers from great ones.

Expert Answer
35 words

STAR: Situation: Nightly job took 6 hr; SLA 2 hr. Task: Optimize. Action: Profiled—found full scan and skew. Partition pruning; broadcast join for dimension; salting for skew. Result: 1.5 hr; 4x improvement. Quantify: Before/after; techniques.

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According to DataEngPrep.tech, this is one of the most frequently asked System Design/Architecture interview questions, reported at 1 company. DataEngPrep.tech maintains a curated database of 1,863+ real data engineering interview questions across 7 categories, verified by industry professionals.

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