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From: wuchong <git@git.apache.org>
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Subject: [GitHub] flink pull request #2653: [FLINK-4469] [table] Add support for user defined ...
Content-Type: text/plain
Message-Id: <20161118084128.2C4FAE9444@git1-us-west.apache.org>
Date: Fri, 18 Nov 2016 08:41:28 +0000 (UTC)
archived-at: Fri, 18 Nov 2016 08:41:33 -0000

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

    https://github.com/apache/flink/pull/2653#discussion_r88617192
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/table.scala ---
    @@ -611,6 +612,130 @@ class Table(
       }
     
       /**
    +    * The Cross Apply returns rows form the outer table (table on the left of the Apply operator)
    +    * that produces matching values from the table-valued function (which is on the right side of
    +    * the operator).
    +    *
    +    * The Cross Apply is equivalent to Inner Join, but it works with a table-valued function.
    +    *
    +    * Example:
    +    *
    +    * {{{
    +    *   class MySplitUDTF extends TableFunction[String] {
    +    *     def eval(str: String): Unit = {
    +    *       str.split("#").foreach(collect)
    +    *     }
    +    *   }
    +    *
    +    *   val split = new MySplitUDTF()
    +    *   table.crossApply(split('c).as('s)).select('a,'b,'c,'s)
    +    * }}}
    +    */
    +  def crossApply(udtf: TableFunctionCall[_]): Table = {
    +    applyInternal(udtf, JoinType.INNER)
    +  }
    +
    +  /**
    +    * The Cross Apply returns rows form the outer table (table on the left of the Apply operator)
    +    * that produces matching values from the table-valued function (which is on the right side of
    +    * the operator).
    +    *
    +    * The Cross Apply is equivalent to Inner Join, but it works with a table-valued function.
    +    *
    +    * Example:
    +    *
    +    * {{{
    +    *   class MySplitUDTF extends TableFunction[String] {
    +    *     def eval(str: String): Unit = {
    +    *       str.split("#").foreach(collect)
    +    *     }
    +    *   }
    +    *
    +    *   val split = new MySplitUDTF()
    +    *   table.crossApply("split('c') as (s)").select("a, b, c, s")
    +    * }}}
    +    */
    +  def crossApply(udtf: String): Table = {
    +    applyInternal(udtf, JoinType.INNER)
    +  }
    +
    +  /**
    +    * The Cross Apply returns rows form the outer table (table on the left of the Apply operator)
    +    * that produces matching values from the table-valued function (which is on the right side of
    +    * the operator).
    +    *
    +    * The Cross Apply is equivalent to Inner Join, but it works with a table-valued function.
    +    *
    +    * Example:
    +    *
    +    * {{{
    +    *   class MySplitUDTF extends TableFunction[String] {
    +    *     def eval(str: String): Unit = {
    +    *       str.split("#").foreach(collect)
    +    *     }
    +    *   }
    +    *
    +    *   val split = new MySplitUDTF()
    +    *   table.outerApply(split('c).as('s)).select('a,'b,'c,'s)
    +    * }}}
    +    */
    +  def outerApply(udtf: TableFunctionCall[_]): Table = {
    +    applyInternal(udtf, JoinType.LEFT_OUTER)
    +  }
    +
    +  /**
    +    * The Outer Apply returns all the rows from the outer table (table on the left of the Apply
    +    * operator), and rows that do not matches the condition from the table-valued function (which
    +    * is on the right side of the operator), NULL values are displayed.
    +    *
    +    * The Outer Apply is equivalent to Left Outer Join, but it works with a table-valued function.
    +    *
    +    * Example:
    +    *
    +    * {{{
    +    *   val split = new MySplitUDTF()
    +    *   table.crossApply("split('c') as (s)").select("a, b, c, s")
    +    * }}}
    +    */
    +  def outerApply(udtf: String): Table = {
    +    applyInternal(udtf, JoinType.LEFT_OUTER)
    +  }
    +
    +  private def applyInternal(udtfString: String, joinType: JoinType): Table = {
    +    val node = ExpressionParser.parseLogicalNode(udtfString)
    +    var alias: Option[Seq[Expression]] = None
    +    val functionCall = node match {
    +      case AliasNode(aliasList, child) =>
    +        alias = Some(aliasList)
    +        child
    +      case _ => node
    +    }
    +
    +    functionCall match {
    +      case call @ UnresolvedTableFunctionCall(name, args) =>
    +        val udtfCall = tableEnv.getFunctionCatalog.lookupTableFunction(name, args)
    +        if (alias.isDefined) {
    +          applyInternal(udtfCall.as(alias.get: _*), joinType)
    +        } else {
    +          applyInternal(udtfCall, joinType)
    +        }
    +      case _ => throw new TableException("Cross/Outer Apply only accept TableFunction")
    +    }
    +  }
    +
    +  private def applyInternal(node: LogicalNode, joinType: JoinType): Table = {
    +    node match {
    +      case udtf: TableFunctionCall[_] =>
    +        udtf.setChild(this.logicalPlan)
    +        new Table(
    +          tableEnv,
    +          Join(this.logicalPlan, udtf.validate(tableEnv), joinType, None,
    +               Some(relBuilder.getCluster.createCorrel())).validate(tableEnv))
    --- End diff --
    
    Good idea!


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