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 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 ...
Get Microsoft® SQL Server 2008 R2 Unleashed now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
