Morningstar Data Engineer Interview Questions

The questions to prepare for a Morningstar Data Engineer interview. Questions from real interview reports rank first. Updated daily.

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SQL & Data ManipulationStart here. 6 questions + 2 drills · ~73 min

Optimizing Large Transaction Table JoinsHard

Explain how to tune a slow PostgreSQL query that joins several large transaction tables using indexes, join strategy, and partitioning.

Joinsperformancesql

Morningstar

Window Ranking in Ticket QueuesMedium

Explain SQL window functions and when to use ROW_NUMBER() versus DENSE_RANK() for ranked ticket analysis.

Window FunctionsRankingrow_number

Morningstar

SQL and Python Work ExamplesMedium

Assesses practical experience combining SQL and Python for data transformation and analysis.

sqlpython

Morningstar

SQL for Risk-Adjusted Top PortfoliosHard

Practice

Practice drill

Rank portfolios by three-month rolling risk-adjusted returns using monthly performance and risk-free rates.

Window Functionsfinancial datacomplex queries

Morningstar

Rolling 7-Day Returns by SegmentMedium

Practice

Practice drill

Calculate daily and rolling 7-day portfolio returns for each user segment using PostgreSQL window functions.

Window FunctionsDate Functionsfinancial data

Morningstar

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Pipelines8 questions · ~70 min

Batch vs Streaming Data ProcessingEasy

Compare batch and streaming data processing, including when each fits best in a pipeline.

Stream ProcessingETLBatch Processing

Morningstar

Backfilling Missing Pipeline DataMedium

Approach for safely backfilling missing data while preserving correctness, idempotency, and data quality.

ETLQuality

Morningstar

Data Quality and Schema EvolutionMedium

Approach for handling schema changes and data quality checks in a high-volume data lake pipeline.

schema evolutionData ModelingQuality

Morningstar

Spark Optimization and PartitioningHard

Tests your ability to optimize Spark workloads using partitioning and performance best practices.

sparkoptimization

Morningstar

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