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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