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From Stefano Baghino <stefano.bagh...@radicalbit.io>
Subject Re: Trying to detecting changes
Date Wed, 20 Apr 2016 14:50:31 GMT
Ok, thanks for the clarification Till.

On Wed, Apr 20, 2016 at 4:46 PM, Till Rohrmann <trohrmann@apache.org> wrote:

> You could use CEP for that. First you would create a pattern of two states
> which matches everything. In the select function you could then check
> whether both elements are different.
>
> However, this would be a little bit of an overkill for this simple use
> case. You could for example simply use a flat map operation which stores
> the last seen element. Then whenever you see a different element you can
> emit a change event.
>
> Cheers,
> Till
>
> On Wed, Apr 20, 2016 at 2:43 PM, Stefano Baghino <
> stefano.baghino@radicalbit.io> wrote:
>
>> Can the CEP library be used for this use case?
>>
>> On Wed, Apr 20, 2016 at 2:02 PM, Aljoscha Krettek <aljoscha@apache.org>
>> wrote:
>>
>>> Hi,
>>> this could be done by implementing a user function that keeps state or
>>> by using windows with a custom Trigger. On only works, however, if you only
>>> have one Kafka partition and if your Flink job is executing with
>>> parallelism=1. Otherwise we don't have any ordering guarantees on streams.
>>>
>>> Cheers,
>>> Aljoscha
>>>
>>> On Wed, 20 Apr 2016 at 12:50 <toletum@toletum.org> wrote:
>>>
>>>> Hi! I'm a beginner in Flink.
>>>> I'm reading from a Kafka topic. In this topic, I receive a character
>>>> each event, like that:
>>>>
>>>> Event.: 1 2 3 4 5 6 7 8 9...
>>>> Data..: A A A B B B B C C...
>>>>
>>>> I would like to do a "trigger" when the character is different than
>>>> before. For example:
>>>> Event º1 fire because of A is different to "null"
>>>> Event º4 fire because of B is different to A
>>>> Event º8 fire because of C is different to B
>>>>
>>>> Could it be possible?
>>>>
>>>
>>
>>
>> --
>> BR,
>> Stefano Baghino
>>
>> Software Engineer @ Radicalbit
>>
>
>


-- 
BR,
Stefano Baghino

Software Engineer @ Radicalbit

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