15.00 - Calculating Multicolumn Demographics - Teradata Database

Teradata Database Design

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

Calculating Multicolumn Demographics

You must have an understanding of the underlying data before you can undertake a legitimate calculation of the demographics for multicolumn situations.

The following table provides some calculation guidelines for determining the number of distinct values in a binary (two column) situation. The guidelines scale as more columns are added to the candidate index.

 

IF distinct column_1 values …

THEN the total number of distinct values in the two‑column index equals …

ELSE the number of distinct values is …

can be paired with distinct values from column_2

the product of the number of distinct values in column_1 and the number of distinct values in column_2

approximately equal to the product of the number of distinct values in column_1 and the average number of values in column_2 that can be paired with a single column_1 value.