See “Choosing the number of steps for highly duplicated values” for more information.
For example, if your table has 5000 rows, and one value in the column that has only one matching row, you may need to request 5000 steps to get a histogram that includes a frequency cell for every distinct value. The actual number of steps is not 5000; it is either the number of distinct values plus one (for dense frequency cells) or twice the number of values plus one (for sparse frequency cells).
