What is the recommended action to improve performance when business-critical functions rely on data extensions used in a query activity?

• A. Avoid indexing on data extensions
• B. Do not index data extensions
• C. Increase the timeout on the query
• D. Use indexing on data extensions used in the query activity

Answer: (D)

Indexing data extensions used in a query activity speeds up how the query retrieves data. By creating an index on the fields that the query filters on or uses in joins, the query engine can locate matching rows quickly instead of scanning the entire extension. This directly reduces execution time and improves reliability for business-critical functions that rely on timely results from that query. Increasing the timeout does not make the query faster; it only allows it to run longer. Avoiding indexing would slow performance overall, especially with large data sets. So, applying indexing to the relevant fields used by the query activity is the best way to boost performance.