17.10 - Duplicate Row Checks for SET Tables with NUPIs - Advanced SQL Engine - Teradata Database

Teradata Vantageā„¢ - Database Design

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
User Guide
Publication ID
B035-1094-171K
Language
English (United States)

Database tables defined with the SET attribute in the CREATE TABLE kind clause do not permit duplicate rows. Any time a row is inserted into a SET table having a NUPI and no uniqueness constraints or indexes, the system performs a duplicate row check.

When Vantage checks for duplicate rows, it considers nulls to be equal, while in SQL conditions, null comparisons evaluate to UNKNOWN. See Inconsistencies in How SQL Treats Nulls for information about how nulls are interpreted by commercially available relational database management systems.