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https://issues.apache.org/jira/browse/FLINK-3311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15151293#comment-15151293
]
ASF GitHub Bot commented on FLINK-3311:
---------------------------------------
Github user rmetzger commented on a diff in the pull request:
https://github.com/apache/flink/pull/1660#discussion_r53240407
--- Diff:
flink-streaming-connectors/flink-connector-cassandra/src/main/java/org/apache/flink/connectors/cassandra/batch/CassandraOutputFormat.java
---
@@ -0,0 +1,126 @@
+/*
+ * 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
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.connectors.cassandra.batch;
+
+import java.io.IOException;
+
+import org.apache.flink.api.common.io.RichOutputFormat;
+import org.apache.flink.api.java.tuple.Tuple;
+import org.apache.flink.configuration.Configuration;
+import org.apache.flink.connectors.cassandra.streaming.ClusterConfigurator;
+
+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.base.Strings;
+import com.google.common.util.concurrent.FutureCallback;
+import com.google.common.util.concurrent.Futures;
+
+public abstract class CassandraOutputFormat<OUT extends Tuple> extends
+ RichOutputFormat<OUT> implements ClusterConfigurator {
+
+ private static final long serialVersionUID = 1L;
+
+ private final String createQuery;
+ private final String insertQuery;
+
+ private transient Cluster cluster;
+ private transient Session session;
+ private transient PreparedStatement ps;
+ private transient FutureCallback<ResultSet> callback;
+ private transient Throwable asyncException = null;
+
+ public CassandraOutputFormat(String insertQuery) {
+ this(null, insertQuery);
+ }
+
+ public CassandraOutputFormat(String createQuery, String insertQuery) {
+ if(Strings.isNullOrEmpty(insertQuery)){
+ throw new IllegalArgumentException("insertQuery cannot
be null or empty");
+ }
+ this.insertQuery = insertQuery;
+ this.createQuery = createQuery;
+ }
+
+ @Override
+ public void configure(Configuration parameters) {
+ }
+
+ @Override
+ public void open(int taskNumber, int numTasks) throws IOException {
+
+ this.cluster = configureCluster(Cluster.builder()).build();
+ this.session = cluster.connect();
+ this.ps = session.prepare(insertQuery);
+ this.callback = new FutureCallback<ResultSet>() {
+
+ @Override
+ public void onSuccess(ResultSet ignored) {
+ }
+
+ @Override
+ public void onFailure(Throwable t) {
+ asyncException = t;
+ }
+ };
+
+ // execute createQuery with only parallelism of 1
+ if(createQuery != null){
+ int parallelism =
getRuntimeContext().getNumberOfParallelSubtasks();
+ if(parallelism > 1) {
+ throw new IllegalStateException("It is allowed
to create the table only with parallelism of 1");
--- End diff --
This effectively means the output format works only with parallelism of 1,
right?
> Add a connector for streaming data into Cassandra
> -------------------------------------------------
>
> Key: FLINK-3311
> URL: https://issues.apache.org/jira/browse/FLINK-3311
> Project: Flink
> Issue Type: New Feature
> Components: Streaming Connectors
> Reporter: Robert Metzger
> Assignee: Andrea Sella
>
> We had users in the past asking for a Flink+Cassandra integration.
> It seems that there is a well-developed java client for connecting into
> Cassandra: https://github.com/datastax/java-driver (ASL 2.0)
> There are also tutorials out there on how to start a local cassandra instance
> (for the tests):
> http://prettyprint.me/prettyprint.me/2010/02/14/running-cassandra-as-an-embedded-service/index.html
> For the data types, I think we should support TupleX types, and map standard
> java types to the respective cassandra types.
> In addition, it seems that there is a object mapper from datastax to store
> POJOs in Cassandra (there are annotations for defining the primary key and
> types)
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