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System Design questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master system design interviews.

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This is a medium difficulty System Design question, commonly asked during Onsite rounds at OpenAI.

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This question is commonly asked for Machine Learning Engineer candidates at OpenAI during technical interviews.

Design Duplicate File Detection | OpenAI Interview Question

Design Duplicate File Detection

Last updated: Apr 12, 2026

Quick Overview

This question evaluates system design and storage engineering skills, including scalable file-processing, efficient I/O and resource management, correctness in content-based duplicate detection, and distributed aggregation.

OpenAI

Apr 3, 2026, 12:00 AM

Machine Learning Engineer

Onsite

System Design

3 solved

Design a system to find duplicate files.

Start with a single-machine version: given a large directory tree, identify groups of files that have identical contents even if their file names and paths are different.

Then discuss how you would optimize and extend the solution to a large distributed storage environment with many machines and a very large number of files.

Your design should address:

How to avoid unnecessary full file reads
How to compare files efficiently and safely
How to manage CPU, memory, and disk I/O
How to support incremental rescans when files are added or modified
How to partition work across machines
How to aggregate and verify duplicate groups in a distributed setting

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