Once and Only Once

A hard SQL interview practice problem on DataDriven. Write and execute real sql code with instant grading.

Domain

SQL

Difficulty

hard

Seniority

L4

Problem

On-call is triaging latency anomalies, where a reading that recurs is routine noise but a reading seen a single time is the real signal. For each endpoint, surface the highest such one-off latency, worst first.

Summary

Repeated readings are noise. The value seen a single time is the signal.

Practice This Problem

Solve this SQL problem with real code execution. DataDriven runs your SQL queries against a real database and grades it automatically.