16.20 - Use EXPLAIN or Visual Explain to Analyze the Usefulness of Secondary Indexes - Teradata Database - Teradata Vantage NewSQL Engine

Teradata Vantage™ SQL Data Definition Language Detailed Topics

Product
Teradata Database
Teradata Vantage NewSQL Engine
Release Number
16.20
Release Date
March 2019
Content Type
Programming Reference
Publication ID
B035-1184-162K
Language
English (United States)

Before a request is processed, the Optimizer estimates comparative costs to determine whether the use of a secondary index offers savings or is plausible. If not, it uses a different access method. You should test the performance of a secondary index before implementing it.

You can use either the SQL EXPLAIN request modifier or the Visual Explain client utility to generate a description of the processing sequence to help determine whether a secondary index should be retained. See Teradata Vantage™ SQL Data Manipulation Language , B035-1146 and Teradata® Visual Explain User Guide, B035-2504.