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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-6196) Support dynamic schema in Table Function
Date Thu, 06 Apr 2017 11:49:41 GMT

    [ https://issues.apache.org/jira/browse/FLINK-6196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15958785#comment-15958785
] 

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

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

    https://github.com/apache/flink/pull/3623#discussion_r110141028
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/utils/UserDefinedFunctionUtils.scala
---
    @@ -358,4 +366,120 @@ 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 = transformLiteralExpressions(params: _*)
    +    val userDefinedResultType = tableFunction.getResultType(arguments)
    +    val resultType = {
    +      if (userDefinedResultType != null) userDefinedResultType
    +      else implicitResultType
    +    }
    +    TableFunctionCall(name, tableFunction, params, resultType)
    +  }
    +
    +  /**
    +    * Transform the expressions to Objects
    +    * Only literal expressions will be transformed, non-literal expressions will be
    +    * translated to nulls.
    +    *
    +    * @param params actual parameters of the function
    +    * @return A java List of the Objects
    +    */
    +  private[table] def transformLiteralExpressions(params: Expression*): java.util.List[AnyRef]
= {
    +    params.map {
    +      case exp: Literal =>
    +        exp.value.asInstanceOf[AnyRef]
    +      case _ =>
    +        null
    +    }
    +  }
    +
    +  /**
    +    * Transform the rex nodes to Objects
    +    * Only literal rex nodes will be transformed, non-literal rex nodes will be
    +    * translated to nulls.
    +    *
    +    * @param rexNodes actual parameters of the function
    +    * @return A java List of the Objects
    +    */
    +  private[table] def transformRexNodes(
    +      rexNodes: java.util.List[RexNode]): java.util.List[AnyRef] = {
    +    rexNodes.map {
    +      case rexNode: RexLiteral =>
    +        val value = rexNode.getValue2
    +        rexNode.getType.getSqlTypeName match {
    +          case SqlTypeName.INTEGER =>
    +            value.asInstanceOf[Long].toInt.asInstanceOf[AnyRef]
    +          case SqlTypeName.SMALLINT =>
    +            value.asInstanceOf[Long].toShort.asInstanceOf[AnyRef]
    +          case SqlTypeName.TINYINT =>
    +            value.asInstanceOf[Long].toByte.asInstanceOf[AnyRef]
    +          case SqlTypeName.FLOAT =>
    +            value.asInstanceOf[Double].toFloat.asInstanceOf[AnyRef]
    +          case SqlTypeName.REAL =>
    +            value.asInstanceOf[Double].toFloat.asInstanceOf[AnyRef]
    +          case _ =>
    --- End diff --
    
    `Timestamp` works fine. When I call `getValue2()` it will generate a `Long` on this. I
will add a test on this.


> 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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