Github user fhussonnois commented on a diff in the pull request: https://github.com/apache/storm/pull/827#discussion_r45238310 --- Diff: external/storm-cassandra/src/main/java/org/apache/storm/cassandra/Murmur3StreamGrouping.java --- @@ -0,0 +1,89 @@ +/** + * 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.storm.cassandra; + +import backtype.storm.generated.GlobalStreamId; +import backtype.storm.grouping.CustomStreamGrouping; +import backtype.storm.task.WorkerTopologyContext; +import backtype.storm.topology.FailedException; +import com.google.common.annotations.VisibleForTesting; +import com.google.common.collect.Lists; +import com.google.common.hash.Hashing; + +import java.io.ByteArrayOutputStream; +import java.io.DataOutputStream; +import java.io.IOException; +import java.util.List; + +/** + * + * Simple {@link backtype.storm.grouping.CustomStreamGrouping} that uses Murmur3 algorithm to choose the target task of a tuple. + * + * This stream grouping may be used to optimise writes to Apache Cassandra. + */ +public class Murmur3StreamGrouping implements CustomStreamGrouping { --- End diff -- Yes, that's right! Actually, I didn't even noticed there is no method like this on component : customGrouping(componentId, customStreamGrouping, fields...). So, one solution could be to pass the indexes of the the partition keys as follows : myBolt.customGrouping("comp", new Murmur3StreamGrouping(0,1)) ?
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