15.00 - Case Study 2 - Teradata Database

Teradata Database Design

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

Case Study 2

The following table indicates the number of distinct occurrences of city column values.

 

City Value

Frequency of Value

Log Frequency of Value

New York

                     4,000

                          3.602

Los Angeles

                     4,000

                          3.602

Chicago

                     4,000

                          3.602

Denver

                     4,000

                          3.602

Paris

                          30

                          1.477

London

                          30

                          1.477

Tokyo

                          30

                          1.477

Rio de Janeiro

                          30

                          1.477

The following histogram graphs the logarithm of the number of rows as a function of row values:

The maximum value for this set is 4,000, but what is the typical value?

It is impossible to determine a typical value for the scenario provided by this case history. When you encounter a situation like this, the optimum solution is to use the worst case as your typical value. In this case, that value is 4,000. Note that the average value for this variable is 2,015, which is not only not a typical value for the distribution of the variable, it is never a value for the variable in this case.

 

Maximum Value

Typical Value

4,000

4,000