17.00 - 17.05 - Unique and Nonunique Primary Indexes - Advanced SQL Engine - Teradata Database

Teradata Vantage™ - Database Administration

Product
Advanced SQL Engine
Teradata Database
Release Number
17.00
17.05
Published
June 2020
Language
English (United States)
Last Update
2021-01-22
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You can define the primary index as unique (UPI) or nonunique (NUPI), depending on whether duplicate values are allowed in the indexed column set.

UPIs provide optimal data distribution and are typically assigned to the primary key for a table. However, the primary key is not necessarily always the best candidate for a primary index.

When a table is designed with a NUPI, consider assigning a uniqueness constraint such as PRIMARY KEY or UNIQUE to the primary or other alternate key of the table. This both enforces uniqueness and enhances retrieval for applications where the primary or other alternate key is frequently used as a selection or join criterion.