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

--------------------------
Ken Krugler
http://www.scaleunlimited.com <http://www.scaleunlimited.com/>
custom big data solutions & training
Hadoop, Cascading, Cassandra & Solr



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