Why does Snowflake advise against adding more than 3–4 columns to a cluster key?

• A. Because data is not going to be clustered correctly
• B. Because it tends to increase costs more than benefits
• C. Because cluster keys must be exactly 3-4 columns
• D. Because more columns have no effect on performance

Answer: (B)

Clustering keys influence how Snowflake organizes data into micro-partitions so that queries can prune what they don’t need to scan. Each additional column in the cluster key adds more criteria that must be maintained and tracked, which increases the overhead of DML operations and metadata management. The real benefit comes only when queries frequently filter on those columns; beyond a few well-chosen columns, the extra pruning you gain tends to be small while the maintenance costs grow. That mismatch between limited extra benefit and rising cost is why keeping cluster keys to around 3–4 columns is recommended. Snowflake isn’t saying you must have exactly that many, and it isn’t saying more columns will never help, but the typical outcome is higher costs with diminishing returns.