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https://issues.apache.org/jira/browse/FLINK-3332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15142948#comment-15142948
]
ASF GitHub Bot commented on FLINK-3332:
---------------------------------------
Github user tillrohrmann commented on a diff in the pull request:
https://github.com/apache/flink/pull/1620#discussion_r52623142
--- Diff:
flink-streaming-connectors/flink-connector-cassandra/src/main/java/org/apache/flink/streaming/connectors/cassandra/CassandraExactlyOnceSink.java
---
@@ -0,0 +1,100 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.flink.streaming.connectors.cassandra;
+
+import com.datastax.driver.core.Cluster;
+import com.datastax.driver.core.PreparedStatement;
+import com.datastax.driver.core.ResultSet;
+import com.datastax.driver.core.ResultSetFuture;
+import com.datastax.driver.core.Session;
+import com.google.common.util.concurrent.FutureCallback;
+import com.google.common.util.concurrent.Futures;
+import org.apache.flink.api.java.tuple.Tuple;
+import org.apache.flink.streaming.runtime.operators.GenericExactlyOnceSink;
+
+/**
+ * Sink that emits its input elements into a Cassandra database. This sink
is integrated with the checkpointing
+ * mechanism to provide exactly once semantics.
+ *
+ * Incoming records are stored within a {@link
org.apache.flink.runtime.state.AbstractStateBackend}, and only committed if a
+ * checkpoint is completed. Should a job fail while the data is being
committed, no exactly once guarantee can be made.
+ * @param <IN>
+ */
+public class CassandraExactlyOnceSink<IN extends Tuple> extends
GenericExactlyOnceSink<IN> {
--- End diff --
Why does it only works for `Tuple` and not a generic type?
> 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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