15.00 - Selectivity Considerations - Teradata Database

Teradata Database Design

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

Selectivity Considerations

Selectivity refers to the percentage of rows in a table containing the same non-unique secondary index value. An index that has high selectivity retrieves few rows. A unique primary index retrieval, for example, is highly selective because it never returns more than one row. An index that has low selectivity retrieves many rows.