Which statement requires a running warehouse to execute?

• A. SELECT MAX(AGE) FROM USERS_TABLE;
• B. SELECT * FROM USERS_TABLE WHERE email='[e-mail]';
• C. SELECT COUNT(*) FROM USERS_TABLE;
• D. EXPLAIN USING TABULAR SELECT * FROM USERS_TABLE WHERE email='[e-mail]';

Answer: (B)

The key idea is that a running warehouse is the compute resource that actually executes a query against data. A statement that retrieves data from a table with a filter on a column requires reading the table data and applying the predicate to locate and return the matching row(s). That data-access operation needs real compute time on a virtual warehouse.

In this case, the query that selects all columns from the table where the email matches a specific value is a direct data retrieval task. It must scan the table (or the relevant parts, using pruning) and return the row that satisfies the condition, which consumes compute on a running warehouse.

The other forms either request a plan (which can be generated without scanning data) or involve aggregation, which, while it does involve computation, is not the same straightforward data fetch with a concrete row predicate. Therefore, the statement that filters by email requires an active warehouse to execute.