September 2010
Intermediate to advanced
1704 pages
111h 8m
English
Up to 200 sample values can be stored in the statistics histogram. Each sample value is called a step. The sample value stored in each step is the endpoint of a range of values. Three values are stored for each step:
• RANGE_ROWS—This indicates how many other rows are inside the range between the current step and the step prior, not including the step values themselves.
• EQ_ROWS—This is the number of rows that have the same value as the sample value. In other words, it is the number of duplicate values for the step.
• Range density—This indicates the number of distinct values within the range. The range density information is actually displayed in two separate columns, DISTINCT_RANGE_ROWS and AVG_RANGE_ROWS:
• DISTINCT_RANGE_ROWS ...