GitHub user kl0u opened a pull request:
https://github.com/apache/flink/pull/1839
Adds watermark emission to the Kafka source by allowing the user to specify
her TimestampExtractor.
This PR allows the user to embed her desired timestampExtractor (or
Watermark emitter) in the Kafka source itself, and it makes the source
responsible for synchronizing between the different partitions/topics with
lagging timestamps.
In more detail, if a task handles two partitions, the first with timestamps
of 0 to 100 and the other from 1000 to 2000, if it were to emit a watermark
with timestamp equal to the maximum timestamp seen, then as soon as an element
from the partition with the 1000 to 2000 timestamps arrives, it would render
all elements in the other partition as late. To avoid this, this source will
monitor the per partition/topic max timestamps, and emit a watermark with a
timestamp equal to the minimum across the max per partition per topic
timestamps. The emission will be done in a periodic or a punctuates way,
depending on the type of the timestamp extractor the user specified.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/kl0u/flink kafka_wm_redesign
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/1839.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #1839
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commit 74dbb5c81ef7793202f151a96dee2ee0bd980a36
Author: kl0u <kklou...@gmail.com>
Date: 2016-03-08T16:35:14Z
Adds watermark emission to the Kafka source by allowing the user to specify
her TimestampExtractor.
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