Your question is Optimize Multi-Terabyte ETL Pipeline. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
You are discussing a past pipeline optimization project and want to show how you approached a large-scale ETL bottleneck. The interviewer is looking for concrete decisions around distributed processing, query tuning, and how you verified that performance improved without breaking data correctness.
Describe a time you had to optimize a slow-running ETL process for a multi-terabyte dataset.