[
https://issues.apache.org/jira/browse/FLINK-3332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15148437#comment-15148437
]
ASF GitHub Bot commented on FLINK-3332:
---------------------------------------
Github user rmetzger commented on a diff in the pull request:
https://github.com/apache/flink/pull/1640#discussion_r52994409
--- Diff:
flink-streaming-connectors/flink-connector-cassandra/src/main/java/org/apache/flink/streaming/connectors/cassandra/CassandraCommitter.java
---
@@ -0,0 +1,77 @@
+/**
+ * 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.ConsistencyLevel;
+import com.datastax.driver.core.Session;
+import com.datastax.driver.core.SimpleStatement;
+import org.apache.flink.streaming.runtime.operators.CheckpointCommitter;
+
+/**
+ * CheckpointCommitter that saves information about completed checkpoints
within a separate table in a cassandra
+ * database.
+ *
+ * Entries are in the form |operator_id | subtask_id |
last_completed_checkpoint|
+ */
+public class CassandraCommitter extends CheckpointCommitter {
+ private final String host;
+ private final String keyspace;
+ private final String table;
+
+ private transient Cluster cluster;
+ private transient Session session;
+
+ public CassandraCommitter(String host, String keyspace, String table) {
+ this.host = host;
+ this.keyspace = keyspace;
+ this.table = table;
+ }
+
+ @Override
+ public void open() throws Exception {
+ cluster = Cluster.builder().addContactPoint(host).build();
+ session = cluster.connect();
+
+ session.execute("CREATE KEYSPACE IF NOT EXISTS " + keyspace + "
with replication={'class':'SimpleStrategy', 'replication_factor':3};");
+ session.execute("CREATE TABLE IF NOT EXISTS " + keyspace + "."
+ table + " (sink_id text, sub_id int, checkpoint_id bigint, PRIMARY KEY
(sink_id, sub_id));");
+ session.executeAsync("INSERT INTO " + keyspace + "." + table +
" (sink_id, sub_id, checkpoint_id) values ('" + operatorId + "', " + subtaskId
+ ", " + -1 + ");");
+ }
+
+ @Override
+ public void close() throws Exception {
+ session.executeAsync("DELETE FROM " + keyspace + "." + table +
" where sink_id='" + operatorId + "' and sub_id=" + subtaskId + ";");
+ session.close();
+ cluster.close();
+ }
+
+ @Override
+ public void commitCheckpoint(long checkpointID) {
+ SimpleStatement s = new SimpleStatement("UPDATE " + keyspace +
"." + table + " set checkpoint_id=" + checkpointID + " where sink_id='" +
operatorId + "' and sub_id=" + subtaskId + ";");
+ s.setConsistencyLevel(ConsistencyLevel.ALL);
+ session.executeAsync(s);
--- End diff --
Why do you execute this asynchronously ? Doesn't this mean we'll never
learn about errors?
> 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.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
