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https://issues.apache.org/jira/browse/FLINK-6988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16146771#comment-16146771
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ASF GitHub Bot commented on FLINK-6988:
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Github user aljoscha commented on the issue:
https://github.com/apache/flink/pull/4239
I did a first high-level review of the code. I think it's good so far!
Before we can merge this, however, we need a few more things around it:
- A section in the Kafka doc about the new exactly-once mode, how it can
be configured etc.
- A big disclaimer (possibly in an "alert" box) about the interplay with
the transaction timeout and what the caveats there are
- A section in the Javadocs about the aforementioned caveats
- A check that ensures that the transaction timeout is set to a reasonably
high setting (say 1 hour) when exactly-once semantics are enabled. (With an
override setting that allows the user to set a lower transaction time out if
they want to.)
Also, this has interplay with #4616 but we can resolve that by merging them
in any order and fixing up the later changes when merging.
> Add Apache Kafka 0.11 connector
> -------------------------------
>
> Key: FLINK-6988
> URL: https://issues.apache.org/jira/browse/FLINK-6988
> Project: Flink
> Issue Type: Improvement
> Components: Kafka Connector
> Affects Versions: 1.3.1
> Reporter: Piotr Nowojski
> Assignee: Piotr Nowojski
>
> Kafka 0.11 (it will be released very soon) add supports for transactions.
> Thanks to that, Flink might be able to implement Kafka sink supporting
> "exactly-once" semantic. API changes and whole transactions support is
> described in
> [KIP-98|https://cwiki.apache.org/confluence/display/KAFKA/KIP-98+-+Exactly+Once+Delivery+and+Transactional+Messaging].
> The goal is to mimic implementation of existing BucketingSink. New
> FlinkKafkaProducer011 would
> * upon creation begin transaction, store transaction identifiers into the
> state and would write all incoming data to an output Kafka topic using that
> transaction
> * on `snapshotState` call, it would flush the data and write in state
> information that current transaction is pending to be committed
> * on `notifyCheckpointComplete` we would commit this pending transaction
> * in case of crash between `snapshotState` and `notifyCheckpointComplete` we
> either abort this pending transaction (if not every participant successfully
> saved the snapshot) or restore and commit it.
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