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Updated weekly · Last refresh Aug 30

Canonical Data Engineer Interview Questions

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

29questions
~4htotal time
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1
PipelinesStart here. 13 questions · ~110 min
Data Quality in ETL PipelinesEasy

Approach for maintaining data quality and integrity across ETL pipelines.

IdempotencyData ModelingQualityCanonical
Structured vs Unstructured DataEasy

Explain how structured and unstructured data differ, and why that matters for pipeline design and downstream processing.

ETLData ModelingQualityCanonical
Diagnose an Integration Pipeline IssueMedium

Structured approach to diagnose failures in an ETL integration, from source extraction through orchestration, data quality, and idempotent recovery.

ToolsDependenciesQualityCanonical
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2
Coding3 questions · ~25 min
Time Complexity of Sorting AlgorithmsEasy

Compare common sorting algorithms by best, average, and worst-case time complexity and explain when each is appropriate.

MathArraysSortingCanonical
Moving Average CalculationMedium

Tests ability to implement windowed calculations correctly and efficiently.

MathArraysSliding WindowCanonical
Python Data DeduplicationMedium

Tests ability to design and implement deduplication logic in Python.

Hash TablesStringsSortingCanonical
3
Behavioral & Leadership11 questions · ~93 min
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4
More topics2 questions · ~17 min
SQL Top 10 Products by SalesEasy
Practice

Aggregate completed SMX product sales and return the top 10 products by units sold.

RankingGroup ByAggregationsCanonical
Optimize a Slow SQL QueryMedium

Tests SQL performance troubleshooting using explain plans, indexing, and query rewrites.

Joinsquery optimizationAggregationsCanonical

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Hands-on SQL practiceWrite and run real queries in the editor. 2 drills · ~20 min
SQL Conversion Rate by CampaignEasy
Practice
Practice drill

Calculate daily campaign conversion rates with conditional aggregation, a CTE, and a campaign dimension join.

Date FunctionsGroup ByAggregationsNianticBrazeOutschool
Monthly Sales Trends by CategoryMedium
Practice
Practice drill

Aggregate monthly sales by product category and use LAG to calculate month-over-month changes.

InfrastructureToolsData WranglingTotal Wine & MoreInc.Benjamin Moore
The finish line: interview-readyComplete all 29 questions plus 2 hands-on drills to finish this plan.