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https://issues.apache.org/jira/browse/FLINK-1906?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14499655#comment-14499655
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Stephan Ewen commented on FLINK-1906:
-------------------------------------
Makes sense.
> Add tip to work around plain Tuple return type of project operator
> ------------------------------------------------------------------
>
> Key: FLINK-1906
> URL: https://issues.apache.org/jira/browse/FLINK-1906
> Project: Flink
> Issue Type: Improvement
> Components: Documentation
> Affects Versions: 0.9
> Reporter: Fabian Hueske
> Priority: Minor
> Labels: starter
>
> The Java compiler is not able to infer the return type of the {{project}}
> operator and defaults to {{Tuple}}. This can cause problems if another
> operator is immediately called on the result of a {{project}} operator such
> as:
> {code}
> DataSet<Tuple5<String,String,String,String,String>> ds = ....
> DataSet<Tuple1<String>> ds2 = ds.project(0).distinct(0);
> {code}
> This problem can be overcome by hinting the return type of {{project}} like
> this:
> {code}
> DataSet<Tuple1<String>> ds2 = ds.<Tuple1<String>project(0).distinct(0);
> {code}
> We should add this description to the documentation of the project operator.
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