Buckets ordered by `date_from` ascending. Empty buckets are omitted — infer gaps by comparing each bucket's `date_to` to the next bucket's `date_from`.
interval
string
Short-form duration of the chosen bucket width (e.g. "1h", "5m", "30s", "1d"). Informational only — use each bucket's `date_from`/`date_to` for follow-up queries.