Re: How can i merge more than one flink stream

2017-07-25 Thread Fabian Hueske
If you are using tumbling time-windows, then the timestamp of the aggregated records emitted from the window are all the maximum timestamp that would have been accepted for the window. For example, if you have an hourly tumbling window, the window from 2 to 3 o'clock would include all timestamps be

Re: How can i merge more than one flink stream

2017-07-25 Thread Jone Zhang
“Consistent” means that in the same time window, the timestamps of the three streams should be kept the same. In my application, I am trying to build an online learning system. I need to join the streams from 1 and 2 on the SAME timestamp to form training samples which will be fed to some online l

Re: How can i merge more than one flink stream

2017-07-24 Thread Jörn Franke
What do you mean by "consistent"? Of course you can do this only at the time the timpstamp is defined (e.g. Using NTP). However, this is never perfect . Then it is unrealistic that they always end up in the same window because of network delays etc. you will need here a global state that is defi

Re: How can i merge more than one flink stream

2017-07-24 Thread Jone Zhang
Thanks for your reply. I have another question: In my situation, each of the three streams contains a local timestamp segment. How can I ensure that their timestamps are consistent in each time window before the merging operation? And how to ensure the arrival of all the streams with consistent tim

Re: How can i merge more than one flink stream

2017-07-19 Thread Kien Truong
Hi, To expand on Fabian's answer, there's a few API for join. * connect - you have to provide a CoprocessFunction. * window join/cogroup - you provide  key selector functions, a time window and a join/cogroup function. With the first method, you have to write more code, in exchange for much mo

Re: How can i merge more than one flink stream

2017-07-19 Thread Fabian Hueske
Hi, there are basically two operations to merge streams. 1. Union simply merges the input streams such that the resulting stream has the records of all input streams. Union is a built-in operator in the DataStream API. For that all streams must have the same data type. 2. Join connects records of

How can i merge more than one flink stream

2017-07-19 Thread Jone Zhang
I have three data streams 1. app exposed and click 2. app download 3. app install How can i merge the streams to create a unified stream,then compute it on time-based windows Thanks