Hi luyj,
Currently, TableAPI does not have the trigger, due to the behavior of the
windows(unbounded, tumble, slide, session) is very clear.The behavior of
each window is as follows:
- Unbounded Window - Each set of keys is a grouping, and each event
triggers a calculation.
- Tumble Window - A tumbling window assigns rows to non-overlapping,
continuous windows of fixed length. Each window outputs one calculation
result.
- Slide Window - A sliding window has a fixed size and slides by a
specified slide interval. If the slide interval is smaller than the window
size, sliding windows are overlapping. Each window outputs one calculation
result.
- Session Window - Session windows do not have a fixed size but their
bounds are defined by an interval of inactivity, i.e., a session window is
closes if no event appears for a defined gap period. Each window outputs
one calculation result.
All of those windows are not hold all the input data, the calculations are
incremental.
About your case, I think you can use `Unbounded Window` and group by a
UDF(time) which return the day unit. e.g.:
> table.groupBy(dateFormat('time, "%Y%d")).select('a.sum)
or
table
> .select('a, dateFormat('time, "%Y%d").cast(Types.STRING) as 'ts)
> .groupBy('ts)
> .select('ts, 'a.sum)
Hope to help you!
Best,
Jincheng
lu yj <lime...@gmail.com> 于2019年3月26日周二 下午4:17写道：
> Hello,
>
> I am using Table API to do some aggregation based on time window.
>
> In DataStream API, there is trigger to control when the aggregation
> function should be invoked. Is there similar thing in Table API?
>
> Because I am using large time window, like a day. I want the intermediate
> result every time a new event is aggregated. Is that possible? And also,
> does it hold all the input data until the window ends?
>
> Thanks!
>
