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From "Henrik Feldt" <henrik.fe...@voiapp.io>
Subject Flink session window not progressing
Date Mon, 29 Apr 2019 17:26:06 GMT
Hi guys,

I'm going a PoC with Flink and I was wondering if you could help me.

I've asked a question here 
https://stackoverflow.com/questions/55907954/flink-session-window-sink-timestamp-not-progressing

with some images. However, in summary my question is this; why doesn't 
my session window progress?

It works great when I run it against historical data, but when I run it 
against a streaming data source (pub/sub) it sometimes gets stuck. In 
this case, it got stuck at exactly 12:00 UTC.

My window is a session window, but one where I bump the last 'edge' of 
the window by different amounts depending on what event type it is. 
Because some events never have other events after them.

You can see the problem the easiest in these graphs, specifically the 
one that stops at 14:00 CEST (12:00 UTC) - with green bars.

![](cid:5D5F9BCB-A282-4161-8DE3-2A711A281E63@voiapp.io "Screenshot 
2019-04-29 at 19.07.09.png")

This graph shows the low-watermark progressing throughout the node in 
the middle (which is also a sink); and this holds for all the nodes in 
the graph. However, the session windowing doesn't progress, despite the 
low-watermark progressing.

![](cid:0C3554DD-0A6E-4F2D-B101-C7F6AD51F0E9@voiapp.io "Screenshot 
2019-04-29 at 19.00.42.png")

Regards,
Henrik

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