histogram tuning factor controls the number of steps SAP ASE analyzes per histogram for update statistics, update index statistics, update all statistics, and create index.
Summary Information 


Default value 
20 
Range of values 
1 – 100 
Status 
Dynamic 
Display level 
Intermediate 
Required role 
System administrator 
Configuration group 
SQL Server Administration 
A value of 1 disables histogram tuning factor.
min (max (400, requested_steps), histogram_tuning_factor X requested_steps)
sp_configure 'histogram tuning factor',20 update statistics tab using 30 valuesSAP ASE analyzes the histogram and compresses it into the resulting histogram according to the following parameters:
The first step is copied unchanged.
The highfrequency steps are copied unchanged.
The consecutive range steps are collapsed into the resulting step, so the total weight of the collapsed step is no bigger than onethirtieth of the value.
Has range steps generated in a way similar for a 30step update statistics, and high frequency ranges are isolated as if the histogram were created with 600 steps.
The total number of steps in the resulting histogram may differ between 30 and 600 values.
For equally distributed data, the value should be very close to 30.
More “frequent” values in the table means more steps in the histogram.
If a column has few different values, all those values may appear as highfrequency cells.
You can achieve the same result by increasing the number of histogram steps to 600, but this uses more resources in the buffer and procedure cache
histogram tuning factor minimizes the resources histograms consume, and increases resource usage only when it is in the best interest for optimization, for example, when there is uneven distribution of data in a column, or highly duplicated values within a column. In this situation, up to 600 histogram steps are used. However, in most cases, histogram tuning factor uses the default value (30 in the example above).