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From Timo Walther <twal...@apache.org>
Subject Re: Appropriate State to use to buffer events in ProcessFunction
Date Wed, 08 Mar 2017 08:55:01 GMT
Hi Yassine,

have you thought about using a ListState? As far as I know, it keeps at 
least the insertion order. You could sort it once your trigger event has 
If you use a RocksDB as state backend, 100+ GB of state should not be a 
problem. Have you thought about using Flink's CEP library? It might fit 
to your needs without implementing a custom process function.

I hope that helps.


Am 07/03/17 um 19:23 schrieb Yassine MARZOUGUI:
> Hi all,
> I want to label events in a stream based on a condition on some future 
> events.
> For example my stream contains events of type A and B and and I would 
> like to assign a label 1 to an event E of type A if an event of type B 
> happens within a duration x of E. I am using event time and my events 
> can be out of order.
> For this I'm using ProcessFunction which looks suitable for my use 
> case. In order to handle out of order events, I'm keeping events of 
> type A in a state and once an event of type B is received, I fire an 
> event time timer in which I loop through events of type A in the state 
> having a timestamps < timer.timestamp, label them and remove them from 
> the state.
> Currently the state is simply a value state containing a 
> TreeMap<Timestamp, EventA>. I'm keeping events sorted in order to 
> effectively get events older than the timer timestamp.
> I wonder If that's the appropriate data structure to use in the value 
> state to buffer events and be able to handle out of orderness, or if 
> there is a more effective implementation, especially that the state 
> may grow to reach ~100 GB sometimes?
> Any insight is appreciated.
> Thanks,
> Yassine

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