16.20 - Unique Indexes - Teradata Database - Teradata Vantage NewSQL Engine

Teradata Vantageâ„¢ SQL Fundamentals

Product
Teradata Database
Teradata Vantage NewSQL Engine
Release Number
16.20
Published
March 2019
Language
English (United States)
Last Update
2019-05-02
dita:mapPath
zce1519094756513.ditamap
dita:ditavalPath
TD_DBS_16_20_Update1.ditaval

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

Teradata Database 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.