Snowflake Certification Practice Test

When should you specify a clustering key and consider reclustering a table?

1. When the table needs a new name.

2. When the order of data loaded matches the clustering key.

3. When the loading order does not match the querying dimension.

4. When there are no joins performed on the table.

The correct answer is: When the loading order does not match the querying dimension.

Specifying a clustering key and considering reclustering a table is particularly important when the loading order of data does not match the dimensions on which queries are being executed. Clustering allows for more efficient data retrieval because it organizes the data in a way that aligns with your querying patterns. When the order of data loaded does not align with how the data will be accessed—meaning the queries might require scanning through partitions of data that are not optimally organized—performance can degrade. Reclustering in this context helps to rearrange the data in a manner that makes future queries faster and more efficient. Therefore, by specifying a clustering key that reflects your querying patterns, you can improve query performance significantly. In contrast, changing a table's name or performing joins on the table are unrelated to the need for effective data organization and optimization through clustering. The order of data loading being aligned with the clustering key, while beneficial, does not necessitate specifying a clustering key or triggering a reclustering action since the data would already be organized efficiently for querying.