When would you usually consider to add clustering key to a table

When would you usually consider to add clustering key to a table

A. The performance of the query has deteriorated over a period of time.

B. The number of users querying the table has increased

C. it is a multi-terabyte size table

D. The table has more than 20 columns

View Answer

Answer: A

Explanation:

A. The performance of the query has deteriorated over a period of time.

Clustering keys in Snowflake are used to optimize the arrangement of data in a table’s micro-partitions. Adding a clustering key can help improve the performance of queries that have become slower over time, especially if this deterioration is due to table growth and suboptimal micro-partition pruning during query execution. This can happen as data becomes more spread out across micro-partitions, leading to larger scans during query execution.

Options B, C, and D may not necessarily justify the need for a clustering key:

B. The number of users querying the table has increased: An increase in the number of users does not inherently require a clustering key. If performance issues arise due to concurrency, other features such as scaling the warehouse or using result caching may be more appropriate.

C. It is a multi-terabyte size table: While large tables could benefit from clustering keys, the size of the table alone isn’t the sole reason to add a clustering key. It would be more about the access patterns, such as frequent filtering on certain columns, that would make a clustering key beneficial.

D. The table has more than 20 columns: The number of columns in a table does not directly impact the need for a clustering key. The decision to add a clustering key should be based on how the data is accessed and queried, not on the column count.

Therefore, adding a clustering key is most commonly considered to address specific performance issues related to data retrieval patterns, not just the size of the table, the number of users, or the number of columns.