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https://issues.apache.org/jira/browse/FLINK-8229?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16285659#comment-16285659
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Fabian Hueske commented on FLINK-8229:
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In the DataSet API, a broadcast variable is computed by an operator of the
program and sent to all operators that require the variable.
This is not possible in a generic DataStream program, because the input is
unbounded and it is not possible to compute a final value for a broadcast
variable. So either, the plan would block, because the operators never receive
a value for the variable or they need to be able to handle updates. An stream
of updates can also be modeled by a co-operator (CoMapFunction,
CoFlatMapFunction, or CoProcessFunction).
I propose to close this issue.
> Cannot use broadcast in StreamingEnvironment
> --------------------------------------------
>
> Key: FLINK-8229
> URL: https://issues.apache.org/jira/browse/FLINK-8229
> Project: Flink
> Issue Type: Improvement
> Reporter: Wind
>
> {code:java}
> @Override
> public <RT> List<RT> getBroadcastVariable(String name) {
> throw new UnsupportedOperationException("Broadcast variables
> can only be used in DataSet programs");
> }
> {code}
> Why not support broadcast variable in Datastream programs ?
> I am not sure if I am right, I guess it has the same mechanism as the dataset
> broadcast variable.
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