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Subject [GitHub] [flink] sunjincheng121 commented on a change in pull request #7196: [FLINK-10974] [table] Add support for flatMap to table API
Date Fri, 19 Apr 2019 07:47:16 GMT
sunjincheng121 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_r276922137
 
 

 ##########
 File path: flink-table/flink-table-planner/src/main/scala/org/apache/flink/table/operations/OperationTreeBuilder.scala
 ##########
 @@ -365,6 +367,53 @@ class OperationTreeBuilder(private val tableEnv: TableEnvironment) {
       mapFunction.asInstanceOf[CallExpression].getFunctionDefinition.getType == SCALAR_FUNCTION
   }
 
+  def flatMap(tableFunction: Expression, child: TableOperation): TableOperation = {
+
+    val resolver = resolverFor(tableCatalog, functionCatalog, child).build()
+    val resolvedTableFunction = resolveSingleExpression(tableFunction, resolver)
+
+    if (!isTableFunction(resolvedTableFunction)) {
+      throw new ValidationException("Only TableFunction can be used in the flatMap operator.")
+    }
+
+    val originFieldNames: Seq[String] =
+      resolvedTableFunction.asInstanceOf[CallExpression].getFunctionDefinition match {
+        case tfd: TableFunctionDefinition =>
+          UserDefinedFunctionUtils.getFieldInfo(tfd.getResultType)._1
+      }
+
+    def getUniqueName(inputName: String, usedFieldNames: Seq[String]): String = {
+      var i = 0
+      var resultName = inputName
+      while (usedFieldNames.contains(resultName)) {
+        resultName = resultName + "_" + i
+        i += 1
+      }
+      resultName
+    }
+
+    val usedFieldNames = child.asInstanceOf[LogicalNode].output.map(_.name).toBuffer
+    val newFieldNames = originFieldNames.map({ e =>
+      val resultName = getUniqueName(e, usedFieldNames)
+      usedFieldNames.append(resultName)
+      resultName
+    })
+
+    val renamedTableFunction = ApiExpressionUtils.call(
+      BuiltInFunctionDefinitions.AS,
+      resolvedTableFunction +: newFieldNames.map(ApiExpressionUtils.valueLiteral(_)): _*)
+    val joinNode = joinLateral(child, renamedTableFunction, JoinType.INNER, Optional.empty())
+    val dropNode = dropColumns(
 
 Review comment:
   `dorpNode` ->`rightNode`, becaust `joinNode`=`leftNode`+`rightNode`. after `dropCloumns()`,
all columns if from `rightNode`. What do you think?

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