Types of Indexes - Teradata Database

Teradata Database Design

Teradata Database
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Types of Indexes

Unique Indexes

A unique index column set, like a primary key column set constraint, enforces a unique value for that column set for each row in a table.

Teradata Database defines two different types of unique index:

  • Unique primary index (UPI)
  • UPIs provide optimal data distribution and, when used, are typically assigned to the primary key for a table.

    UPIs are described in detail in “Unique Primary Indexes” on page 213.

  • Unique secondary index (USI)
  • USIs guarantee that each complete index value is unique, while ensuring that data access based on it is always at most a two-AMP operation. A USI is typically assigned to the primary key for a table when the table does not have a UPI for the primary key and enforcement by the system of a primary key or unique constraint is a requirement.

    USIs are described in detail in “Unique Secondary Indexes” on page 405.