Western Governors University (WGU) ITCL3203 D321 AWS Practice Exam

The choice indicating that using the Scan operation in DynamoDB consumes a lot of read capacity units (RCUs) is correct because the Scan operation reads every item in the table or index sequentially, which inherently entails a significant consumption of read capacity. This is because, unlike a query that can use the partition key to directly access specific items, a scan does not leverage any keys for efficiency. Instead, it involves traversing the entire dataset, resulting in high resource usage, especially in larger tables.

This method is less efficient than targeted queries, as it essentially fetches all the data and applies any filters after the fact, consuming more read capacity units as it processes each item in the table. Thus, if your goal is to minimize the costs associated with read capacity units or to maximize performance, relying on Scan operations can be detrimental, particularly for larger datasets.

The other options do not accurately express the limitations or disadvantages of the Scan operation in the same way. For example, while scans do not require a specific partition key, they also allow filtering of results, though with the underlying cost implications. Therefore, focusing on the high consumption of read capacity units best encapsulates the downside of using Scan in DynamoDB.