17.10 - Primary Keys and Primary Indexes - Advanced SQL Engine - Teradata Database

Teradata Vantageā„¢ - SQL Fundamentals

Advanced SQL Engine
Teradata Database
Release Number
Release Date
July 2021
Content Type
Programming Reference
Publication ID
English (United States)

The following table summarizes the differences between keys and indexes, using the primary key and primary index for purposes of comparison.

Primary Key Primary Index
Important element of logical data model. Not used in logical data model.
Used to maintain referential integrity. Used to distribute and retrieve data.
Must be unique to identify each row. Can be unique or nonunique.
Values cannot change. Values can change.
Cannot be null. Can be null.
Does not imply access path. Defines the most common access path.
Not required for physical table definition. Required for physical table definition.