TumblingWindowLifetime

Moves each event into a fixed, non-overlapping window, ready for an aggregate.

TumblingWindowLifetime(size) is HoppingWindowLifetime(size, size). It snaps each event’s start up to the next multiple of size (or keeps it, if it is already on a boundary) and gives it a lifetime of size. An event with start in (k·size − size, k·size] therefore lives in [k·size, k·size + size): everything that happened in one window becomes visible together, when that window closes.

In the diagram (size 4), the events at 1, 2 and 4 all live in [4,8); the event at 7 lives in [8,12) and the one at 9 in [12,16). Note that the event at exactly 4 lands with the events at 1 and 2, not with 7.

Follow it with an aggregate to compute per-window results: see Count.

See also: HoppingWindowLifetime, Count (tumbling window), GroupApply