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Top 50 Data Engineer Interview Questions

The 50 most important questions to prepare for Data Engineer interviews. Questions from real interview reports rank first. Updated weekly.

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1
CodingStart here. 25 questions · ~563 min
Merge Two Sorted ArraysEasy
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Merge two sorted arrays into one sorted array using a two-pointer linear scan.

ArraysSortingTwo PointersDenodo3Y HealthDropbox
Merge Two Sorted Linked ListsMedium
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Merge two sorted singly linked lists into one sorted list by relinking existing nodes.

RecursionLinked ListsSortingNeoDoctoNAVA TECHU.S. Pharmacopeia
First Non-Repeating CharacterMedium
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Find the first non-repeating character in a string using frequency counting and a second pass in O(n) time.

Hash TablesStringsSearchingCogniteWalgreens Boots AllianceForeFlight
Two Sum with TargetEasy
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Use a hash map to find two array elements that sum to a target in O(n) time.

Hash TablesArraysStringsEsystemsBungalowSide
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2
SQL & Data Manipulation25 questions · ~563 min
Top Customers by Sales RevenueEasy
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Use GROUP BY and SUM to rank the top 10 customers by total revenue from a single sales table.

RankingGroup ByAggregationsMastekSageThornburg Investment
Second Highest Without AggregatesMedium
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Find the second highest salary in each department without using aggregate functions.

SubqueriesRankingSelf-JoinsMicron Memory Malaysia Sdn BhdInformaticaExusia
Second Highest Trader SalaryEasy
Practice
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Find the second highest distinct salary from a single table using basic PostgreSQL ordering and limiting.

SubqueriesRankingSortingAntraWNSState Street
SQL Duplicate DetectionMedium
Practice
Recently asked

Find duplicate customer profiles by grouping on identifying fields and returning only repeated records.

Group ByHavingAggregationsUniversity of Southern CaliforniaCircle Internet FinancialRevature
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