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From tole...@toletum.org
Subject Re[2]: Trying to detecting changes
Date Thu, 21 Apr 2016 11:29:58 GMT
Thanks Till,

At the end, I'm going to use a countWindowAll(2,1) and RichAllWindowFunction.

On mié., abr. 20, 2016 at 16:46, Till Rohrmann  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.
On Wed, Apr 20, 2016 at 2:43 PM, Stefano Baghino  wrote:
Can the CEP library be used for this use case?
On Wed, Apr 20, 2016 at 2:02 PM, Aljoscha Krettek  wrote:
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.
On Wed, 20 Apr 2016 at 12:50  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?
Stefano Baghino

Software Engineer @ Radicalbit

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