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ETL optimization Interview Questions

The most frequently asked ETL optimization questions across all roles and companies, ranked by real interview frequency. Updated daily.

28questions
~4htotal time
135companies covered
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1
PipelinesStart here. 26 questions · ~208 min
Optimize Multi-Terabyte ETL PipelineMedium
Recently asked

Explain how you improved a slow ETL pipeline on multi-terabyte data, including bottleneck analysis, tuning choices, and validation.

ETL optimizationdata processingperformanceWishXcceleratedAnthropic
Cost Optimization in Cloud WarehousesHard
Recently asked

Explain how to reduce cloud warehouse costs while tuning ETL workloads, queries, storage, and compute allocation.

cost optimizationETL optimizationdata warehouseWhatnot
Spark Internals and TuningHard

Explain Spark internals and diagnose a slow job using execution plans, stage metrics, partition analysis, and targeted optimizations.

distributed computingETL optimizationbottleneck optimizationHHackerRank
Spark Internals and TransformationsHard

Explain Spark execution internals, transformation lineage, actions, shuffles, and performance tuning decisions.

distributed computingETL optimizationdata skewnessHHackerRank
Optimize Slow Spark JobsHard

Diagnose a slow Spark job with Spark UI, identify the bottleneck, and apply targeted performance improvements.

distributed computingETL optimizationperformanceHHackerRank
Optimizing an ETL PipelineMedium

Assesses ETL performance troubleshooting and improvement under real constraints.

ETL optimizationchallengesNBCUniversal Advertising Products & Solutions
ETL Optimization Across the WorkflowMedium

Tests your end-to-end optimization mindset across ETL stages in a GCP-based workflow.

data pipelineETL optimizationETLGloballogic
Optimize ETL for ScaleMedium

Tests your ability to optimize ETL/ELT performance and design for scalability.

ETL optimizationperformancescalabilityPublicis Production
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2
More topics2 questions · ~16 min
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Hands-on SQL practiceWrite and run real queries in the editor. 3 drills · ~30 min
Optimizing Slow JSON ProcessingMedium
Practice
Practice drill

Extract and aggregate completed JSON events efficiently while filtering batches before processing payload data.

database optimizationlarge datasetsperformanceKeystone
Optimizing Slow QueriesMedium
Practice
Practice drill

Analyze slow query workloads with filtered aggregation and an owner lookup.

Performance Tuningdatabase optimizationdata processingWaymo
Mitigate Data Skew in JoinsHard
Practice
Recently asked
Practice drill

Detect a heavily skewed join key and produce a deterministically salted join result for more balanced large-scale processing.

database optimizationlarge datasetsJoinsDatabricks
The finish line: interview-readyComplete all 28 questions plus 3 hands-on drills to finish this plan.