4767e3a6___Documentation__8_4__pg_stats__Description
[Name] histogram_bounds [Type] anyarray [Description] 
A list of values that divide the column's values into groups of approximately equal population. The values in most_common_vals, if present, are omitted from this histogram calculation. (This column is NULL if the column data type does not have a < operator or if the most_common_vals list accounts for the entire population.)
PostgreSQL: Documentation: 8.4: pg_stats