Aggregate Tumbling
Description
This page describes the behavior specific to aggregations in the tumling window. For concepts and configuration common to all time-window aggregations, see Aggregations in time windows.
A tumbling window divides time into consecutive, non-overlapping periods of a fixed length. For example, with a 10-minute window, events may be collected into windows such as 10:00–10:10, 10:10–10:20, 10:20–10:30, and so on. Each event belongs to one such window.
Unlike a sliding window, the window boundaries are determined by time and do not move when a new event arrives.
Aggregate Tumbling specific
For simplicity, all events share the same groupBy value ("purple")
In the On each event emit mode the incoming event is enriched with the aggregate calculated from events received so far in its current window.. Because the events are enriched, rather than a new aggregation event is produced, the #input variable is available in the nodes downstream.
In the After window closes emit mode incoming events do not continue downstream. When the window closes, a new aggregate event is emitted for each group. Consequntly, all the variables defined before the node (including #input and #inputMeta) will not be available downstream.
Parameters and configuration:
Parameters common to all windows are described here.
| Name | Description |
|---|---|
windowLength | Length of the tumbling window. Must be a positive duration. |
emitWhen | Determines when the event with the result of the aggregation will be emitted. Possible values are: - On each event - After window closes - After window closes, also when no event for key - we produce extra zero aggregate for each key when no data arrived |