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https://issues.apache.org/jira/browse/FLINK-3179?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15150343#comment-15150343
]
ASF GitHub Bot commented on FLINK-3179:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/1553#discussion_r53151692
--- Diff:
flink-optimizer/src/main/java/org/apache/flink/optimizer/operators/GroupReduceWithCombineProperties.java
---
@@ -87,19 +92,39 @@ public DriverStrategy getStrategy() {
return DriverStrategy.SORTED_GROUP_REDUCE;
}
- @Override
public SingleInputPlanNode instantiate(Channel in, SingleInputNode
node) {
if (in.getShipStrategy() == ShipStrategyType.FORWARD) {
// adjust a sort (changes grouping, so it must be for
this driver to combining sort
- if (in.getLocalStrategy() == LocalStrategy.SORT) {
- if
(!in.getLocalStrategyKeys().isValidUnorderedPrefix(this.keys)) {
- throw new RuntimeException("Bug:
Inconsistent sort for group strategy.");
+ if(in.getSource().getOptimizerNode() instanceof
PartitionNode) {
+ // Inject a combiner before the partition node
+ Channel toCombiner = new
Channel(in.getSource());
--- End diff --
bad variable name. This channel will not lead to the combiner.
> Combiner is not injected if Reduce or GroupReduce input is explicitly
> partitioned
> ---------------------------------------------------------------------------------
>
> Key: FLINK-3179
> URL: https://issues.apache.org/jira/browse/FLINK-3179
> Project: Flink
> Issue Type: Bug
> Components: Optimizer
> Affects Versions: 0.10.1
> Reporter: Fabian Hueske
> Assignee: ramkrishna.s.vasudevan
> Priority: Critical
> Fix For: 1.0.0, 0.10.2
>
>
> The optimizer does not inject a combiner if the input of a Reducer or
> GroupReducer is explicitly partitioned as in the following example
> {code}
> DataSet<Tuple2<String,Integer>> words = ...
> DataSet<Tuple2<String,Integer>> counts = words
> .partitionByHash(0)
> .groupBy(0)
> .sum(1);
> {code}
> Explicit partitioning can be useful to enforce partitioning on a subset of
> keys or to use a different partitioning method (custom or range partitioning).
> This issue should be fixed by changing the {{instantiate()}} methods of the
> {{ReduceProperties}} and {{GroupReduceWithCombineProperties}} classes such
> that a combine is injected in front of a {{PartitionPlanNode}} if it is the
> input of a Reduce or GroupReduce operator. This should only happen, if the
> Reducer is the only successor of the Partition operator.
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