Microsoft® SQL Server 2012 Unleashed

The Statistics Histogram

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 in the RANGE_HI_KEY column is the endpoint of a range of values. Four 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 ...