Four Window Types on the Event-Time Axis (Tumbling, Hopping, Sliding, Session)
one shared event-time scale · the same stream of events, four ways of grouping them into windows
event
window
fixed 1-min window (for contrast)
Tumbling
fixed size, no overlap
[0,1)
[1,2)
[2,3)
[3,4)
[4,5)
[5,6)
[6,7)
[7,8)
[8,9)
[9,10)
each event belongs to exactly one window
Hopping
fixed size, fixed hop
each window is 5 min long
windows start 1 min apart
[0,5)
[1,6)
[2,7)
[3,8)
[4,9)
[5,10)
1 min hop
overlap provides smoothing
Sliding
slides with each event
fixed [3,4)
fixed [7,8)
5-min sliding window [3.0, 8.0)
4.5 min apart — different fixed windows
e1 = 3.0 min
e2 = 7.5 min
window follows the events
Session
gap-based,
variable width
session A
session B
session C
same rule
30 min inactivity → session ends
no fixed duration
0
1
2
3
4
5
6
7
8
9
10
shared event-time scale
event time (minutes) →