Sample output for histograms

Histogram for column:               "city"
Column datatype:                    varchar(20)
Requested step count:               20
Actual step count:                  20

optdiag first prints summary data about the histogram, as shown in Table 37-8.

Table 37-8: Histogram summary statistics

Row label

Information provided

Histogram for column

Name of the column.

Column datatype

Datatype of the column, including the length, precision and scale, if appropriate for the datatype.

Requested step count

Number of steps requested for the column.

Actual step count

Number of steps generated for the column.

This number can be less than the requested number of steps if the number of distinct values in the column is smaller than the requested number of steps.

Histogram output is printed in columns, as described in Table 37-9.

Table 37-9: Columns in optdiag histogram output


Information provided


Number of the step.


Weight of the step.


<, <=, or =, indicating the limit of the value. Operators differ, depending on whether the cell represents a range cell or a frequency call.


Upper boundary of the values represented by a range cell or the value represented by a frequency count.

No heading is printed for the Operator column.