[jira] [Created] (FLINK-1906) Add tip to work around plain Tuple return type of project operator

[Shang Yuanchun (Jira)]

Fabian Hueske created FLINK-1906:
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             Summary: 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


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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