Which feature does a Primary Index (PI) provide in Teradata?

A Primary Index (PI) in Teradata is crucial for uniquely identifying each row within a table. The primary index serves as a unique identifier for records, ensuring that when data is accessed or queried, each row can be retrieved without ambiguity. This uniqueness is fundamental since it allows Teradata to efficiently manage and locate rows in a large database environment, ensuring data integrity and facilitating error-free data retrieval operations.

While some databases might allow multiple rows with the same value in other contexts, the primary index is specifically designed to uniquely define and locate each row, which prevents duplication in the PID context. This feature is vital for data consistency and enabling efficient access patterns that Teradata utilizes.

Other options do not accurately describe the primary index's function. For example, guaranteeing uniform distribution of rows is not an inherent feature of the primary index itself; rather, it's more aligned with the concept of a Primary Distribution. Sorting rows for better performance is associated with secondary indexes or ordering clauses, and, as mentioned, a primary index does not allow duplicate values. Each of these points reinforces the core purpose of the primary index in maintaining unique row identification in Teradata.