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https://issues.apache.org/jira/browse/FLINK-9031?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16407877#comment-16407877
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Stephan Ewen commented on FLINK-9031:
-------------------------------------
Hmmm, looking at the execution plans you shared, this seems still a bit
puzzling.
Could you add two screenshots from the web UI showing what the executed
dataflow looks like for both cases?
> DataSet Job result changes when adding rebalance after union
> ------------------------------------------------------------
>
> Key: FLINK-9031
> URL: https://issues.apache.org/jira/browse/FLINK-9031
> Project: Flink
> Issue Type: Bug
> Components: DataSet API, Local Runtime, Optimizer
> Affects Versions: 1.3.1
> Reporter: Fabian Hueske
> Priority: Critical
> Attachments: Person.java, RunAll.java, newplan.txt, oldplan.txt
>
>
> A user [reported this issue on the user mailing
> list|https://lists.apache.org/thread.html/075f1a487b044079b5d61f199439cb77dd4174bd425bcb3327ed7dfc@%3Cuser.flink.apache.org%3E].
> {quote}I am using Flink 1.3.1 and I have found a strange behavior on running
> the following logic:
> # Read data from file and store into DataSet<POJO>
> # Split dataset in two, by checking if "field1" of POJOs is empty or not, so
> that the first dataset contains only elements with non empty "field1", and
> the second dataset will contain the other elements.
> # Each dataset is then grouped by, one by "field1" and other by another
> field, and subsequently reduced.
> # The 2 datasets are merged together by union.
> # The final dataset is written as json.
> What I was expected, from output, was to find only one element with a
> specific value of "field1" because:
> # Reducing the first dataset grouped by "field1" should generate only one
> element with a specific value of "field1".
> # The second dataset should contain only elements with empty "field1".
> # Making an union of them should not duplicate any record.
> This does not happen. When i read the generated jsons i see some duplicate
> (non empty) values of "field1".
> Strangely this does not happen when the union between the two datasets is
> not computed. In this case the first dataset produces elements only with
> distinct values of "field1", while second dataset produces only records with
> empty field "value1".
> {quote}
> The user has not enable object reuse.
> Later he reports that the problem disappears when he injects a rebalance()
> after a union resolves the problem. I had a look at the execution plans for
> both cases (attached to this issue) but could not identify a problem.
> Hence I assume, this might be an issue with the runtime code but we need to
> look deeper into this. The user also provided an example program consisting
> of two classes which are attached to the issue as well.
>
>
>
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