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https://issues.apache.org/jira/browse/FLINK-2361?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14644576#comment-14644576
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Stephan Ewen commented on FLINK-2361:
-------------------------------------
A fast way to check this is to run a variant where you set
{{setSolutionSetUnManaged(true)}} on the delta iteration. Then the compacting
hash table is not used.
> flatMap + distinct gives erroneous results for big data sets
> ------------------------------------------------------------
>
> Key: FLINK-2361
> URL: https://issues.apache.org/jira/browse/FLINK-2361
> Project: Flink
> Issue Type: Bug
> Components: Gelly
> Affects Versions: 0.10
> Reporter: Andra Lungu
>
> When running the simple Connected Components algorithm (currently in Gelly)
> on the twitter follower graph, with 1, 100 or 10000 iterations, I get the
> following error:
> Caused by: java.lang.Exception: Target vertex '657282846' does not exist!.
> at
> org.apache.flink.graph.spargel.VertexCentricIteration$VertexUpdateUdfSimpleVV.coGroup(VertexCentricIteration.java:300)
> at
> org.apache.flink.runtime.operators.CoGroupWithSolutionSetSecondDriver.run(CoGroupWithSolutionSetSecondDriver.java:220)
> at
> org.apache.flink.runtime.operators.RegularPactTask.run(RegularPactTask.java:496)
> at
> org.apache.flink.runtime.iterative.task.AbstractIterativePactTask.run(AbstractIterativePactTask.java:139)
> at
> org.apache.flink.runtime.iterative.task.IterationTailPactTask.run(IterationTailPactTask.java:107)
> at
> org.apache.flink.runtime.operators.RegularPactTask.invoke(RegularPactTask.java:362)
> at org.apache.flink.runtime.taskmanager.Task.run(Task.java:559)
> at java.lang.Thread.run(Thread.java:722)
> Now this is very bizzare as the DataSet of vertices is produced from the
> DataSet of edges... Which means there cannot be a an edge with an invalid
> target id... The method calls flatMap to isolate the src and trg ids and
> distinct to ensure their uniqueness.
> The algorithm works fine for smaller data sets...
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