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From Alessandro Tagliapietra <tagliapietra.alessan...@gmail.com>
Subject Window aggregation skipping some data
Date Wed, 17 Jul 2019 05:17:55 GMT
transformValuesHello everyone,

I've an issue trying to window data. I'm sending on a topic the same exact
data for 2 different keys, however key number 1 is acting properly, key
number 2 isn't.

As you can see here
sending 4 messages for each key,
the first 3 messages of each key all have the values to 0, the 4th has
different values.

is the code I have (there are more things before and after but I've
narrowed down the issue here).
is the output i see in the console.

Basically what's happening is, in the first piece of code I just use a
store + transformValues to generate from a stream of data a stream of
pairs, so e.g. 1, 2, 3, 4 becomes (1,2), (2,3), (3,4) and so on.
After that stream I log all the sensor + values I get (in the foreach) and
out of the 8 total messages, which get flatMapped into 16 single messages I
send I see 16 logs, which means that all messages
that I've received went through that part.

Now the problem comes after, first I use groupByKey to be able to then
window each key independently, then I use my aggregate function, it's as
this point that I don't see all the messages that I've expected to receive
from the previous step.
As you can see from the log key 1 has its log called 8 times (4 messages
each with 2 metrics flatmapped to 8 messages), key 2 instead has that log
called only 3 times.
At first I thought maybe it was skipping some values because of the
suppress, but both keys have the same values so it should either suppress
both or none, plus all messages are ordered and the timestamp extractor
reads the timestamp from the message.

Anyone has any idea on what could be the problem?

Alessandro Tagliapietra

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