DoorDash USA Data Engineer Interview Questions

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

Explain OLTP vs OLAP designs, including schema shape, workload patterns, and when each is appropriate in a data platform.

Second Highest Trader Salary

Easy

Find the second highest distinct salary from a single table using basic PostgreSQL ordering and limiting.

SubqueriesRankingSorting

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Window Ranking in Ticket Queues

Medium

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

Window FunctionsRankingrow_number

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Data Modeling for Fitness App

Hard

Tests ability to design schemas and modeling choices for analytical use cases.

JoinsData WranglingData Modeling

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Prioritizing Across Competing Client Projects

Easy

Tests prioritization under pressure across multiple projects, including trade-off judgment, stakeholder communication, and ownership of outcomes.

OwnershipPrioritization

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Tests understanding of data structures and correct pointer or reference manipulation.

Common Algorithm and Application

Easy

Tests algorithm knowledge and ability to connect an algorithm to a real problem.

SearchingSortingGreedy

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O(n) Python Solution

Medium

Tests algorithmic thinking and ability to optimize time complexity in Python.

Hash TablesArraysTwo Pointers

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