[jira] [Commented] (FLINK-10974) Add FlatMap to TableAPI

[ASF GitHub Bot (JIRA)]

    [ 
https://issues.apache.org/jira/browse/FLINK-10974?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16712304#comment-16712304
 ] 

ASF GitHub Bot commented on FLINK-10974:
----------------------------------------

dianfu commented on a change in pull request #7196: [FLINK-10974] [table] Add 
support for flatMap to table API
URL: https://github.com/apache/flink/pull/7196#discussion_r239688529
 
 

 ##########
 File path: 
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/table.scala
 ##########
 @@ -999,6 +1006,121 @@ class Table(
     new OverWindowedTable(this, overWindows.toArray)
   }
 
+  /**
+    * Performs a flatMap operation with an user-defined table function.
+    *
+    * Scala Example:
+    * {{{
+    *   class MyFlatMapFunction extends TableFunction[Row] {
+    *     def eval(str : String) {
+    *       if (str.contains("#")) {
+    *         val splits = str.split("#")
+    *         collect(Row.of(splits(0), splits(1)))
+    *       }
+    *     }
+    *
+    *     def getResultType(signature: Array[Class[_]]): TypeInformation[_] =
+    *       Types.ROW(Types.STRING, Types.STRING)
+    *   }
+    *
+    *   val func = new MyFlatMapFunction
+    *   table.flatMap(func('c)).as('a, 'b)
+    * }}}
+    *
+    * Java Example:
+    * {{{
+    *   class MyFlatMapFunction extends TableFunction<Row> {
+    *     public void eval(String str) {
+    *       if (str.contains("#")) {
+    *         String[] splits = str.split("#");
+    *         collect(Row.of(splits[0], splits[1]));
+    *       }
+    *     }
+    *
+    *     public TypeInformation getResultType(Class[] signature) {
+    *       return Types.ROW(Types.STRING, Types.STRING);
+    *     }
+    *   }
+    *
+    *   TableFunction func = new MyFlatMapFunction();
+    *   tableEnv.registerFunction("func", func);
+    *   table.flatMap("func(c)").as("a, b");
+    * }}}
+    */
+  def flatMap(tableFunction: Expression): Table = {
+    unwrap(tableFunction, tableEnv) match {
+      case _: TableFunctionCall =>
+      case _ => throw new ValidationException("Only TableFunction can be used 
in flatMap.")
+    }
+
+    // rename output fields names to avoid ambiguous name
+    val originalCall = 
UserDefinedFunctionUtils.createLogicalFunctionCall(tableEnv, tableFunction)
+    val originalOutputFieldNames = originalCall.output.map(_.name)
+    val usedFieldNames: mutable.HashSet[String] =
+      logicalPlan.output.foldLeft(mutable.HashSet[String]()) { (s, o) => s += 
o.name }
+
+    val newOutputFieldNames = originalOutputFieldNames.zipWithIndex.map { case 
(name, index) =>
+      val newName = if (usedFieldNames.contains(name)) {
+        index + "_" + usedFieldNames.mkString("_") + "_" + name
 
 Review comment:
   OK. Make sense.

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> Add FlatMap to TableAPI
> -----------------------
>
>                 Key: FLINK-10974
>                 URL: https://issues.apache.org/jira/browse/FLINK-10974
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Table API &amp; SQL
>            Reporter: sunjincheng
>            Assignee: Dian Fu
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.8.0
>
>
> Add FlatMap operator to Table API as described in [Google 
> doc|https://docs.google.com/document/d/1tnpxg31EQz2-MEzSotwFzqatsB4rNLz0I-l_vPa5H4Q/edit#heading=h.q23rny2iglsr].
> The usage：
> {code:java}
> val res = tab
>    .flatMap(fun: TableFunction)  // output has columns 'a, 'b, 'c
>    .select('a, 'c)
> {code}



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