fsk119 commented on a change in pull request #14111:
URL: https://github.com/apache/flink/pull/14111#discussion_r529190059
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File path: docs/dev/table/connectors/kafka.md
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@@ -249,6 +249,15 @@ Besides enabling Flink's checkpointing, you can also
choose three different mode
Please refer to [Kafka documentation]({% link dev/connectors/kafka.md
%}#kafka-producers-and-fault-tolerance) for more caveats about delivery
guarantees.
+### Per-partition-watermark Source
+
+Flink supports to emit per-partition-watermark for Kafka. Using this feature,
watermarks are generated inside the Kafka consumer. The per-partition-watermark
are merged in
+the same way as watermarks are merged on stream shuffles. The output watermark
of the source is determined by the minimum watermark among the partitions it
reads. Considering a watermark assigner
+advance the watermark according to the event-time on the records. If some
partitions in the topics are idle, the watermark assigner will not advance. You
can alleviate this problem by
+setting appropriate [idelness timeouts]({{ site.baseurl
}}/dev/event_timestamps_watermarks.html#dealing-with-idle-sources).
Review comment:
You are right. I modify the link:
[table.exec.source.idle-timeout](https://ci.apache.org/projects/flink/flink-docs-master/dev/table/config.html#table-exec-source-idle-timeout)
and [Kafka watermark
strategies](https://ci.apache.org/projects/flink/flink-docs-master/dev/event_timestamps_watermarks.html#watermark-strategies-and-the-kafka-connector).
The page [Kafka watermark
strategies](https://ci.apache.org/projects/flink/flink-docs-master/dev/event_timestamps_watermarks.html#watermark-strategies-and-the-kafka-connector)
is much clear to explain the watermark mechanism.
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