In my Structured Streaming, I set the watermark to 1 hour.
I am doing window operation for each 10 min.
I received a later event 20 min late.
Will the corresponding window will be calculated or not?
Watermark allows late arriving data to be considered for inclusion against already computed results for a period of time using windows. Its premise is that it tracks to a point in time before which it is assumed no more late events are supposed to arrive, but if they do, they are none-the-less discarded. There are various modes of operation.
Excellent examples on https://spark.apache.org/docs/latest/structured-streaming-programming-guide.html#window-operations-on-event-time with nice diagrams to complement.
Your question: Yes, that example you quote will include the late data, as it is in this case as you describe it within the window of 1 hr.