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Re: Always trigger calculation of a tumble window in Flink SQL


You might come up with some magical self join that could do the trick - join/window join the the aggregation result with self and then aggregate it again. I don’t know if that’s possible (probably you would need to write custom aggregate function) and would be inefficient. It will be easier to convert result of your SQL query into a DataStream and process it with a simple/custom DataStream operator.


> On 5 Nov 2018, at 10:17, yinhua.dai <yinhua.2018@xxxxxxxxxxx> wrote:
> We have a requirement that always want to trigger a calculation on a timer
> basis e.g. every 1 minute.
> *If there are records come in flink during the time window then calculate it
> with the normal way, i.e. aggregate for each record and getResult() at end
> of the time window.*
> *If there are no records come in flink during the time window, then send the
> last calculated result.*
> I know that Flink will not trigger the calculation in the second case(when
> no records come in the system during the time window), if there a solution
> for me in Flink SQL?
> --
> Sent from: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/