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https://issues.apache.org/jira/browse/FLINK-4575?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16249312#comment-16249312
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Fabian Hueske commented on FLINK-4575:
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I'm not sure about extending the DataSet API for such special cases. In fact,
I'd rather remove the support for built-in aggregation functions on Tuples in
the future as well.
IMO, the DataSet API is a rather low-level API that should provide the tools to
implement custom functions based on {{MapFunction}}, {{GroupReduceFunction}},
etc.
Functionality for built-in aggregation function is much better covered by the
Table API or SQL support. In fact, it is very easy to convert a {{DataSet}}
into a {{Table}} and vice-versa.
> DataSet aggregate methods should support POJOs
> ----------------------------------------------
>
> Key: FLINK-4575
> URL: https://issues.apache.org/jira/browse/FLINK-4575
> Project: Flink
> Issue Type: Improvement
> Components: DataSet API
> Reporter: Gabor Gevay
> Priority: Minor
> Labels: starter
>
> The aggregate methods of DataSets (aggregate, sum, min, max) currently only
> support Tuples, with the fields specified by indices. With
> https://issues.apache.org/jira/browse/FLINK-3702 resolved, adding support for
> POJOs and field expressions would be easy: {{AggregateOperator}} would create
> {{FieldAccessors}} instead of just storing field positions, and
> {{AggregateOperator.AggregatingUdf}} would use these {{FieldAccessors}}
> instead of the Tuple field access methods.
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