Answer: Pruning

The correct answer is D (Pruning). Snowflake uses pruning as the primary technique to limit the number of micro-partitions scanned by each query. Pruning leverages metadata stored about each micro-partition (min/max values, null counts, etc.) to automatically eliminate micro-partitions that cannot contain relevant data for a given query. This significantly improves query performance by reducing I/O operations. Option A (B-tree) is incorrect as Snowflake doesn't use traditional B-tree indexes like relational databases. Option B (Indexing) is misleading since Snowflake's approach is metadata-based pruning rather than traditional indexing. Option C (Map reduce) is unrelated to micro-partition scanning optimization and refers to a different distributed computing paradigm. The community discussion shows 100% consensus on answer D, with references to official Snowflake documentation confirming pruning as the correct technique.

Author: LeetQuiz Editorial Team