Snowflake prunes micro-partitions based on a predicate with a subquery, even if the subquery results in a constant.

• A. True
• B. False
• C. Not specified
• D. Only for certain subquery types

Answer: (B)

Pruning relies on zone maps that summarize each micro-partition with min/max values and is safe only when the predicate can be evaluated using those statistics alone. A predicate that contains a subquery requires computing that subquery’s value before you can decide if a partition could contain matching rows, which the pruning logic does not do. Even if the subquery happens to return a constant, the overall predicate still depends on data in the partitions, and relying on a constant subquery would not provide a deterministic, partition-level decision. For effective pruning, keep predicates simple and directly on the column values (the keys Snowflake uses for zone maps). Therefore, this statement is false.