17.10 - Unique Indexes - Advanced SQL Engine - Teradata Database

Teradata Vantageā„¢ - SQL Fundamentals

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
Programming Reference
Publication ID
B035-1141-171K
Language
English (United States)

A unique index, like a primary key, has a unique value for each row in a table.

Teradata defines two different unique indexes:

  • Unique primary index (UPI)

    UPIs provide optimal data distribution and are typically assigned to the primary key for a table. When a NUPI makes better sense for a table, then the primary key is frequently assigned to be a USI.

  • Unique secondary index (USI)

    USIs guarantee that each complete index value is unique, while ensuring that data access based on it is always a two-AMP operation.