What is a key function of a Unique Primary Index (UPI)?

The key function of a Unique Primary Index (UPI) is to ensure that each row in a table is uniquely identifiable by a specific index column. This unique key allows Teradata to efficiently manage data access and retrieval. A UPI not only prevents duplicate rows in the indexed column by enforcing uniqueness but also plays an essential role in data distribution across the system’s nodes.

The unique constraint of the UPI is crucial as it directly influences the performance and efficiency of data retrieval operations. Because the UPI ensures that there are no duplicates in its indexed columns, it enables Teradata to evenly distribute rows throughout the system based on the indexed column values. This uniform distribution enhances performance by ensuring that the workload is balanced across all nodes.

The other options focus on different functionalities that do not accurately represent the specific role of a UPI. While it may seem that preventing duplication addresses the uniqueness aspect, the emphasis of the key function in this context highlights data distribution, which is fundamental to Teradata's architecture.