Snowflake Certification Practice Test 2025 - Free Snowflake Exam Practice Questions and Study Guide

The presence of queries running slower than expected is a general indicator that a clustering key may be needed for a large table. In a data warehousing environment, when queries take longer than anticipated, it often points to inefficiencies in how data is organized. The clustering key helps to optimize the storage and retrieval of data by reducing the amount of data that needs to be scanned when executing queries. This is particularly important for large tables, where data might be spread out across multiple storage locations, leading to slower query performance.

While the other options can reflect various issues within a database, they do not specifically indicate the need for a clustering key as clearly as the performance of queries. For example, a low clustering ratio might show that rows are spread out in a way that can affect query performance, but it doesn’t inherently lead to the conclusion that a clustering key is required unless it's also affecting query response time. Similarly, tables that have not been modified or those close to storage capacity do not directly imply the necessity for a clustering key, as they may not necessarily have an impact on query execution speed.