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From Till Rohrmann <trohrm...@apache.org>
Subject Re: Within interval for CEP - Wall Clock based or Event Timestamp based?
Date Mon, 15 Aug 2016 07:48:32 GMT
Hi,

at the moment the CEP operator using EventTime only processes elements
after it has received a watermark which is larger than the timestamp of the
elements. In case of late arrivals it might make sense to directly process
these events. This should decrease the latency a bit (for this case).

Cheers,
Till

On Fri, Aug 12, 2016 at 10:29 PM, Sameer W <sameer@axiomine.com> wrote:

> Thanks Max - Especially the last part about late events.
>
> Sameer
>
> On Fri, Aug 12, 2016 at 4:23 AM, Maximilian Michels <mxm@apache.org>
> wrote:
>
>> Hi Sameer,
>>
>> That depends on the time characteristic you have chosen. If you have
>> set it to event time [1] then it will use event time, otherwise the
>> default is to use processing time.
>>
>> When using event time, the element's timestamp is used to assign it to
>> the specified time windows in the patterns, regardless of the time it
>> actually arrives. The only exception being if the element arrives
>> after the Watermark, then only the single element will be processed
>> according to the patterns.
>>
>> Cheers,
>> Max
>>
>> [1] env.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);
>>
>> On Thu, Aug 11, 2016 at 12:39 AM, Sameer W <sameer@axiomine.com> wrote:
>> > Hi,
>> >
>> > I am using EventTime but when the records get into the CEP PatternStream
>> > does the WITHIN interval refer to the wall clock time or the timestamps
>> > embedded in the event stream?
>> >
>> > If I provide WITHIN(Time.Seconds(5)) and in processing time I am getting
>> > events with timestamps in the range of 10 seconds (due to upstream
>> emits),
>> > are all those events considered part of the pattern of their timestamps
>> > matter?
>> >
>> > Thanks,
>> > Sameer
>>
>
>

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