15.00 - High Selectivity Index - Teradata Database

Teradata Database Design

prodname
Teradata Database
vrm_release
15.00
category
User Guide
featnum
B035-1094-015K

High Selectivity Index

If deptno is a high selectivity index, where few employee rows share the same deptno value, then using deptno for retrieval provides better performance than a full‑table scan. Because of these selective conditions, the Optimizer specifies NUSI access for request processing when it is less costly than a full‑table scan.