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https://issues.apache.org/jira/browse/FLINK-3332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15140971#comment-15140971
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ASF GitHub Bot commented on FLINK-3332:
---------------------------------------
GitHub user zentol opened a pull request:
https://github.com/apache/flink/pull/1620
[FLINK-3332] Cassandra connector
This PR adds an Exactly-Once Cassandra Sink.
The Exactly-once guarantee is made by saving incoming records in the
OperatorState, and only committing them into Cassandra when a checkpoint
completes. Note that a job failure while the data is being committed will cause
duplicate data to be committed, but the chance of this happening is much
smaller than for a naive At-Least-once implementation.
The CassandraExactlyOnceSink is implemented as a custom operator to get
access to the Statebackend. Values are committed with single inserts using a
PreparedStatement that is supplied by the user, similiar to the Batch
JDBC-Outputformat.
The Exactly-Once logic is completely contained in a GenericExactlyOnceSink
class that can be used by virtually every sink, requiring no knowledge about
the checkpointing mechamism.
The CassandraExactlyOnceSink and GenericExactlyOnceSink are covered by
tests that use the OneInputStreamTaskHarness to generate a task environment,
verifying that stored data is discarded when a state is restored; all data is
being committed when a notify is missed; and of course that everything works
when nothing goes wrong.
Note: This PR currently subsumes #1609 (the change to
ResultPartitionWriter), so that the tests run properly.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/zentol/flink 3332_cassandra
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/1620.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 #1620
----
commit 64f0b32c9292f1c5957badbcee30476b663eb5a1
Author: zentol <[email protected]>
Date: 2016-02-10T13:14:18Z
[FLINK-3332] Cassandra connector
----
> Provide an exactly-once Cassandra connector
> -------------------------------------------
>
> Key: FLINK-3332
> URL: https://issues.apache.org/jira/browse/FLINK-3332
> Project: Flink
> Issue Type: Improvement
> Components: Streaming Connectors
> Reporter: Robert Metzger
> Assignee: Chesnay Schepler
>
> With FLINK-3311, we are adding a Cassandra connector to Flink.
> It would be good to also provide an "exactly-once" C* connector.
> I would like to first discuss how we are going to implement this in Flink.
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