What is the typical consequence of including more than the recommended number of columns or expressions in a clustering key?

• A. It improves pruning
• B. It increases costs more than benefits
• C. It has no effect
• D. It reduces query performance only for large tables

Answer: (B)

Adding more columns or expressions to a clustering key than recommended tends to bring diminishing pruning benefits while increasing maintenance costs. Clustering keys help Snowflake prune micro-partitions, but each extra column adds complexity to how data is organized and how clustering metadata is maintained. The result is that the incremental improvement in filtering is small or negligible, while the overhead—more metadata, more frequent or heavier clustering work, and potential increases in data scanned for upkeep—drives up costs. So, the overall effect is that the costs rise relative to the benefits. This is why the typical consequence is that costs increase more than the benefits.