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Top 50 performance Interview Questions

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

50questions
~14htotal time
1,017companies covered
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1
SQL & Data ManipulationStart here. 23 questions · ~393 min
Optimizing Complex SQL JoinsHard
Practice
Recently asked

Build an efficient PostgreSQL report that aggregates partitioned project events and costs without join multiplication.

database optimizationJoinsperformanceMcKinsey &
SQL: Top Bottleneck StageMedium
Practice

Rank workflow stages by average processing time and return the top bottleneck for each workflow type.

Window FunctionsRankingperformanceOscar HealthB Lab Global
Analyzing Operations Bottlenecks with SQLHard
Practice

Use multi-level CTEs, joins, and LAG to identify Samsung regional inventory shortages and late deliveries.

JoinsperformanceAggregationsSamsung ElectronicsApeel Sciences
Mitigate Data Skew in JoinsHard
Practice
Recently asked

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

database optimizationlarge datasetsJoinsDatabricks
Optimize Slow Multi-Join QueryHard
Practice

Optimize a PostgreSQL query with multiple joins and aggregations over large tables while preserving correct filtered totals.

database optimizationJoinsperformanceGoogle
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2
Coding14 questions · ~239 min
Debounce From ScratchMedium
Practice

Simulate trailing-edge debouncing for Informatica asset search events using timestamps and a quiet-period state machine.

debouncingperformancefunctionsInformaticaRobinhood
Optimize Slow SQL with JoinsHard
Practice
Recently asked

Use dynamic programming to minimize intermediate results when ordering joins and independent window computations.

Window FunctionsCodingJoinsDatabricks
Compute Best Times Per ObstacleEasy
Practice

Compute the minimum completion time for every obstacle across Headway assessment attempts using a column-wise scan.

function implementationperformanceHeadway
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3
Behavioral & Leadership8 questions · ~137 min
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4
Pipelines5 questions · ~85 min
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