Hi Jürgen,

That makes sense to me.

Anyone from the Flink team want to comment on (a) if there is a way to get the 
current key in the timer callback without using an explicit ValueState that’s 
maintained in the processElement() method, and (b) if not, whether that could 
be added to the context?


— Ken

> On Feb 4, 2018, at 6:14 AM, Jürgen Thomann <juergen.thom...@innogames.com> 
> wrote:
> Hi Ken,
> thanks for your answer. You're right and I'm doing it already that way. I 
> just hoped that I could avoid the ValueState (I'm using a MapState as well 
> already, which does not store the key) and get the key from the provided 
> Context of the ProcessFunction. This would avoid having the ValueState and 
> setting it in the processElement just to know the key in the onTimer 
> function. 
> In the current way I have to check the ValueState for every element if the 
> key is already set or just set it every time again the processElement method 
> is invoked.
> Best,
> Jürgen
> On 02.02.2018 18:37, Ken Krugler wrote:
>> Hi Jürgen,
>>> On Feb 2, 2018, at 6:24 AM, Jürgen Thomann <juergen.thom...@innogames.com 
>>> <mailto:juergen.thom...@innogames.com>> wrote:
>>> Hi,
>>> I'm currently using a ProcessFunction after a keyBy() and can't find a way 
>>> to get the key.
>> Doesn’t your keyBy() take a field (position, or name) to use as the key?
>> So then that same field contains the key in the 
>> ProcessFunction.processElement(in, …) parameter, yes?
>>> I'm currently storing it in a ValueState<String> within processElement
>> If you’re using a ValueState, then there’s one of those for each unique key, 
>> not one for the operation.
>> I.e. the ValueState for key = “one” is separate from the ValueState for key 
>> = “two”.
>> You typically store the key in the state so it’s accessible in the onTimer 
>> method.
>>> and set it all the time, so that I can access it in onTimer(). Is there a 
>>> better way to get the key? We are using Flink 1.3 at the moment.
>> The ValueState (what you used in processElement) that you’re accessing in 
>> the onTimer() method is also scoped by the current key.
>> So assuming you stored the key in the state inside of your processElement() 
>> call, then you should have everything you need.
>> — Ken
>> PS - Check out 
>> https://www.slideshare.net/dataArtisans/apache-flink-training-datastream-api-processfunction
>> <https://www.slideshare.net/dataArtisans/apache-flink-training-datastream-api-processfunction>
Ken Krugler
custom big data solutions & training
Hadoop, Cascading, Cassandra & Solr

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