AggregationGroup

Buckets the instant of field by unit in timeZone: a bucket's key is the epoch milliseconds of the instant at which the local unit period containing the record begins, in that period's own UTC offset (a week begins on Monday; a day, week, month, quarter or year at its first local midnight, or where a transition puts it). So a bucket never starts after its records, the hour a daylight-saving fall-back repeats is two buckets, and the hour a spring-forward skips is none.

Groups by one calendar part of the field's instant in timeZone, such as the weekday or the hour, so records from different days fall into one bucket. Keys are integers from AggregationDatePart's fixed domain; dense fills every key of that domain that has no records with the empty value of each metric.

Buckets the numeric value of field, or of expression when the group names one instead.

Groups by the value of field, or of expression when the group names one instead.

The grouped field; null only for a TERMS or HISTOGRAM group whose input is an expression.

The computed input of a TERMS or HISTOGRAM group in place of its field, or null.

Where field is read when the query expands elements: null (the innermost element, relative to its container) or AggregationGroupScope.ROOT (a root field, by its absolute path), so a count of elements can be grouped by a field of the record they belong to, such as its creation day. Without elements both read the root.