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Updated weekly · Last refresh Aug 30

Costar Data Analyst Interview Questions

The questions to prepare for a Costar Data Analyst interview. Questions from real interview reports rank first. Updated weekly.

21questions
~3htotal time
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1
SQL & Data ManipulationStart here. 4 questions + 2 drills · ~54 min
Top Customers by Sales RevenueEasy
Practice

Use GROUP BY and SUM to rank the top 10 customers by total revenue from a single sales table.

RankingGroup ByAggregationsCostar
Customer Orders: LEFT vs INNER JOINEasy

Explain how INNER JOIN and LEFT JOIN differ, and when to use each for matched-only versus all-left-row analysis.

JoinsData WranglingGroup ByCostar
Optimize SQL Query PerformanceHard

Tests ability to diagnose bottlenecks and apply indexing, query rewriting, and execution-plan driven tuning.

database managementCostar
SQL Average Selling PriceMedium
Practice
Practice drill

Calculate weighted average selling prices by product using a date-range join, aggregation, and NULL handling.

leetcodesqlCostarCostar Group
Basic SQL and String ReverseEasy
Practice
Practice drill

Reverse Costar property search strings with PostgreSQL and flag rows whose stored expected value does not match.

sql queriesstring manipulationCostar
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2
Pipelines5 questions · ~43 min
Visualization Tools for Analytics PipelinesEasy

Discuss which visualization tools fit different analytics pipeline needs, and why warehouse integration and monitoring matter.

ToolsData ModelingQualityCostar
Data Quality in ETL PipelinesEasy

Approach for maintaining data quality and integrity across ETL pipelines.

IdempotencyData ModelingQualityCostar
Troubleshooting Broken DashboardsMedium

Tests diagnostic skills to isolate data, transformation, and visualization issues affecting dashboard reliability.

ToolsData WranglingQualityCostar
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3
Behavioral & Leadership10 questions · ~86 min
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4
More topics2 questions · ~17 min
Data-Driven Product Recommendation ApproachMedium

A structured approach for turning a product business problem into a clear, evidence-based recommendation.

User NeedsValue PropositionUse CasesCostar
Trends and Anomalies DetectionMedium

Tests your data analysis skills for exploratory insights and anomaly detection.

Leading IndicatorsDiagnosisTime SeriesCostar

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