Histogram cells

When you create an index, a histogram is created on the first column of the index. The histogram stores information about the distribution of values in the column. Then you can use update statistics to generate statistics for the minor keys of a compound index and columns used in unindexed search clauses.

The histogram for a column contains data in a set of steps or cells. You can specify the number of cells can when the index is created or when the update statistics command is run. For each cell, the histogram stores a column value and a weight for the cell.

There are two types of cells in histograms:

For more information on histograms, see “Histogram displays”.