elasticsearch-js/docs/reference/api/RollupHistogramGrouping.md

Interface RollupHistogramGrouping

Name	Type	Description
fields	Fields	The set of fields that you wish to build histograms for. All fields specified must be some kind of numeric. Order does not matter.
interval	long	The interval of histogram buckets to be generated when rolling up. For example, a value of 5 creates buckets that are five units wide ( 0-5, 5-10, etc). Note that only one interval can be specified in the histogram group, meaning that all fields being grouped via the histogram must share the same interval.