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Persistent Systems Interview Questions

The questions to prepare for Persistent Systems interviews, across all roles. Questions from real interview reports rank first. Updated weekly.

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1
SQL & Data ManipulationStart here. 5 questions · ~56 min
Second Highest Without AggregatesMedium
Practice
Recently asked

Find the second highest salary in each department without using aggregate functions.

SubqueriesRankingSelf-JoinsPersistent Systems
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2
Coding5 questions · ~56 min
Sliding Window Rate LimiterMedium
Practice

Implement an exact sliding-window rate limiter using a queue to decide allow/deny per request.

Hash TablesQueueArraysPersistent Systems
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3
Machine Learning5 questions · ~56 min
Supervised vs Unsupervised LearningEasy

Explain how supervised and unsupervised learning differ, and ground the distinction in a practical ML example.

Unsupervised LearningFeature EngineeringBias-Variance TradeoffPersistent Systems
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4
Product Sense5 questions · ~56 min
Turn Feedback Into New FeaturesMedium

Approach for turning user feedback into a well-scoped feature, with clear prioritization, MVP definition, and success metrics.

User ResearchFeature PrioritizationUser NeedsPersistent Systems
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5
Execution5 questions · ~56 min
Prioritize Work Under Tight DeadlinesEasy
Recently asked

Explain how you prioritize competing work under time pressure while making trade-offs and keeping stakeholders aligned.

Trade-offsRoadmappingScope ManagementPersistent Systems
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6
Pipelines5 questions · ~56 min
Batch vs Stream Processing Trade-offsMedium
Recently asked

Compare batch and stream processing across latency, complexity, cost, and data quality in a modern analytics pipeline.

InfrastructureStream ProcessingETLPersistent Systems
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7
More topics20 questions · ~224 min
Approach to Underperforming ModelsMedium

Structured approach for diagnosing an underperforming model and deciding whether to fix data, thresholding, calibration, or the model.

PrecisionAccuracyRecallPersistent Systems
Critical Metrics for Product LaunchMedium

Choose the most important launch metrics, balancing early signals, long-term outcomes, and a clear KPI hierarchy.

KPIsConversion RateLeading IndicatorsPersistent Systems
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