#spark

Coalesce function in SQL - explain

Create partitioned table

Describe how Dataproc integrates with BigQuery for processing large datasets.

Duplicate characters in a string (e.g., '123a!' to '112233aa!!').

Explain Dynamic Partition Pruning error and how to fix it.

Implement a recursive query for hierarchy (employee-manager). Explain the termination guarantees, depth limits, and when a recursive CTE becomes a scalability bottleneck. What alternatives exist for graph-scale hierarchies in Spark or a data lake?

Explain how partitioning and bucketing in Hive/Spark optimize queries. What are the trade-offs in bucket count, partition cardinality, and small-file problem? When does over-partitioning or over-bucketing become counterproductive?

Explain how to implement cumulative sum in SQL.