Selecting a Secondary Index
When assigning columns to be a secondary index for a table, there are numerous factors to consider, the most important of all being the selectivity of the index.
While USI retrievals are always very efficient, the efficiency of NUSI retrievals varies greatly depending on their selectivity.
You can use the Teradata Index Wizard client utility to assist your selection of secondary and single‑table join indexes for a table. The utility recommends a set of indexes based on specific query workloads you supply. The Teradata Index Wizard can also validate its recommendations to ensure they actually provide the benefits expected. See Teradata Index Wizard User Guide for further information about how to use the utility and SQL Request and Transaction Processing for information about how the utility performs its component tasks.