Your question is Optimize SQL for Large Data. 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).
How would you optimize a SQL query to improve performance when dealing with large datasets?
Explain how you would diagnose the bottleneck, interpret an execution plan, and decide among indexing, partitioning, predicate pushdown, join changes, query rewrites, and incremental processing. Demonstrate your approach with SQL and describe how you would validate performance improvements in a production ETL or ELT pipeline.