[jira] [Updated] (FLINK-18683) Support @DataTypeHint for TableFunction output types

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-18683?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

ASF GitHub Bot updated FLINK-18683:
-----------------------------------
    Labels: pull-request-available  (was: )

> Support @DataTypeHint for TableFunction output types
> ----------------------------------------------------
>
>                 Key: FLINK-18683
>                 URL: https://issues.apache.org/jira/browse/FLINK-18683
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Table SQL / API
>            Reporter: Fabian Hueske
>            Assignee: Timo Walther
>            Priority: Minor
>              Labels: pull-request-available
>
> For ScalarFunctions, the return type of an eval method can be declared with a {{@DataTypeHint}}:
> {code:java}
> @DataTypeHint("INT")
> public Integer eval(Integer value) {
>   return value * 2;
> }{code}
> This does not work for TableFunctions because the {{@DataTypeHint}} annotation refers to the {{void}} return type. Hence, {{TableFunction}} {{eval()}} methods must always be annotated with the more complex {{@FunctionHint}} method.
> However, I think that context, it is clear that the {{@DataTypeHint}} annotation refers to the actual return type of the table function (the type parameter of {{TableFunction<OUT>}}).
> We could consider allowing {{@DataTypeHint}} annotations also on {{TableFunction}} classes (defining the output type of all eval methods) and {{eval()}} methods.



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