SQL Database Engine with Virtual Functions

Problem Overview

Implement a SQL database engine using virtual functions (C++ or similar OOP language). The task involves designing and implementing query operators (e.g., Scan, Filter/Select, Project, Join, Aggregate) as a class hierarchy where a base operator class defines a virtual interface (e.g., next() or open/next/close iterator…

• 3 candidate-reported follow-ups — the exact probes interviewers asked, with the trigger for each
• The rest of the problem statement — full requirements, constraints, and edge cases
• Approach and trade-offs — what passing candidates did, and the mistakes that sink people