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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-6196) Support dynamic schema in Table Function
Date Wed, 29 Mar 2017 09:00:50 GMT

    [ https://issues.apache.org/jira/browse/FLINK-6196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15946752#comment-15946752
] 

ASF GitHub Bot commented on FLINK-6196:
---------------------------------------

Github user KurtYoung commented on a diff in the pull request:

    https://github.com/apache/flink/pull/3623#discussion_r108624761
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/utils/UserDefinedFunctionUtils.scala
---
    @@ -358,4 +366,116 @@ object UserDefinedFunctionUtils {
         InstantiationUtil
           .deserializeObject[UserDefinedFunction](byteData, Thread.currentThread.getContextClassLoader)
       }
    +
    +  /**
    +    * Build a TableFunctionCall, a name and a sequence of params will determine a unique
    +    * [[TableFunctionCall]]
    +    *
    +    * @param name function name
    +    * @param implicitResultType If no result type returned, it will use this type.
    +    * @param params The input expressions
    +    * @return A unique [[TableFunctionCall]]
    +    */
    +  private[table] def buildTableFunctionCall(
    +      name: String,
    +      tableFunction: TableFunction[_],
    +      implicitResultType: TypeInformation[_],
    +      params: Expression*): TableFunctionCall = {
    +    val arguments = expressionsToArguments(params: _*)
    +    val userDefinedResultType = tableFunction.getResultType(arguments)
    +    val resultType = {
    +      if (userDefinedResultType != null) userDefinedResultType
    +      else implicitResultType
    +    }
    +    TableFunctionCall(name, tableFunction, params, resultType)
    +  }
    +
    +  /**
    +    * Transform the expressions or rex nodes to Objects
    +    * Only literal expressions will be passed, nulls for non-literal ones
    +    *
    +    * @param params actual parameters of the function
    +    * @return A java List of the Objects
    +    */
    +  private[table] def expressionsToArguments(params: Expression*): java.util.List[AnyRef]
= {
    --- End diff --
    
    rename to transformLiteralExpresssions to better fits the purpose?


> Support dynamic schema in Table Function
> ----------------------------------------
>
>                 Key: FLINK-6196
>                 URL: https://issues.apache.org/jira/browse/FLINK-6196
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table API & SQL
>            Reporter: Zhuoluo Yang
>            Assignee: Zhuoluo Yang
>
> In many of our use cases. We have to decide the schema of a UDTF at the run time. For
example. udtf('c1, c2, c3') will generate three columns for a lateral view. 
> Most systems such as calcite and hive support this feature. However, the current implementation
of flink didn't implement the feature correctly.



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