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https://issues.apache.org/jira/browse/FLINK-1237?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14214408#comment-14214408
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ASF GitHub Bot commented on FLINK-1237:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/incubator-flink/pull/207#discussion_r20421929
--- Diff:
flink-core/src/main/java/org/apache/flink/api/common/functions/Partitioner.java
---
@@ -0,0 +1,36 @@
+/*
+ * 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.api.common.functions;
+
+/**
+ * Function to implement a custom partition assignment for keys.
+ *
+ * @param <K> The type of the key to be partitioned.
+ */
+public interface Partitioner<K> extends java.io.Serializable {
--- End diff --
Does it make sense to add another method ``getMaxNumPartititions()`` to
check at plan construction time if the the DOP is high enough for the
partitioner? Otherwise the program will fail at runtime, if I'm not mistaken.
> Add custom partitioners for shuffle steps
> -----------------------------------------
>
> Key: FLINK-1237
> URL: https://issues.apache.org/jira/browse/FLINK-1237
> Project: Flink
> Issue Type: Improvement
> Reporter: Till Rohrmann
> Assignee: Stephan Ewen
>
> It would be helpful to be able to specify a custom partitioner for shuffle
> steps. This would users allow to control how their data is distributed across
> the cluster. Especially in situations where the number of data records is
> equal to the number of slots it might be a possibility to avoid skewed data
> distributions due to the default hashing function.
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