Esper - detect event after absence

问题:

I found out that it is possible to detect the absence of an event using for example: select * from pattern [every EventX -> (timer:interval(10 sec) and not EventX)], but is it also possible to detect the presence of an event after it was absent? Using prior perhaps? And is it possible to use one statement for detecting both absence and presence? Thanks in advance!

回答1:

Its sounds like you are looking for this

every EventX -> (timer:interval(10 sec) and not EventX) -> Event X

...adding some time interval withing which the event should arrive...

every EventX -> (timer:interval(10 sec) and not EventX) -> Event X where timer:within(10)

Try an outer join to detect with multiple patterns:

select * from pattern[...].win:length_batch(1) as pattern1 full outer join pattern[...].win:length_batch(1) as pattern2