Distributed SQL and Query Scaling Questions

Principles and practices for running and optimizing SQL queries in distributed query engines and cloud data warehouses. Candidates should understand how distributed execution affects query performance including partitioning strategies, shuffle operations, data skew, partition pruning, and cost based optimization in engines such as Spark SQL, Presto, and BigQuery. This topic includes designing queries to minimize data movement, choosing appropriate partition keys, leveraging cluster resources efficiently, and interpreting execution plans and job stages to diagnose bottlenecks in large scale queries.