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https://issues.apache.org/jira/browse/FLINK-6196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15978695#comment-15978695
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ASF GitHub Bot commented on FLINK-6196:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3623#discussion_r112679780
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/schema/DeferredTypeFlinkTableFunction.scala
---
@@ -0,0 +1,68 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.table.plan.schema
+
+import java.lang.reflect.Method
+import java.util
+
+import org.apache.calcite.rel.`type`.{RelDataType, RelDataTypeFactory}
+import org.apache.flink.api.common.typeinfo.TypeInformation
+import org.apache.flink.table.functions.utils.UserDefinedFunctionUtils
+import org.apache.flink.table.functions.{TableFunction => FlinkUDTF}
+
+import scala.collection.JavaConversions._
+
+/**
+ * A Deferred Type is a Table Function which the result type hasn't been
determined yet.
+ * It will determine the result type after the arguments are passed.
+ *
+ * @param tableFunction The Table Function instance
+ * @param evalMethod The eval() method of the [[tableFunction]]
+ * @param implicitResultType Implicit result type.
+ */
+class DeferredTypeFlinkTableFunction(
+ val tableFunction: FlinkUDTF[_],
+ val evalMethod: Method,
+ val implicitResultType: TypeInformation[_])
+ extends FlinkTableFunction(tableFunction, evalMethod) {
+
+ val paramTypeInfos = evalMethod.getParameterTypes.toList
+
+ override def getResultType(arguments: util.List[AnyRef]):
TypeInformation[_] = {
+ determineResultType(arguments)
+ }
+
+ override def getRowType(
+ typeFactory: RelDataTypeFactory,
+ arguments: util.List[AnyRef]): RelDataType = {
+ val resultType = determineResultType(arguments)
+ val (fieldNames, fieldIndexes, _) =
UserDefinedFunctionUtils.getFieldInfo(resultType)
+ UserDefinedFunctionUtils.buildRelDataType(typeFactory, resultType,
fieldNames, fieldIndexes)
+ }
+
+ private def determineResultType(arguments: util.List[AnyRef]):
TypeInformation[_] = {
+ val resultType = tableFunction.getResultType(arguments, paramTypeInfos)
--- End diff --
Here we use the parameter types of `eval()`. This is different from the
logic in `UserDefinedFunctionUtils`. I think we should make this consistent
because users should expect consistent behavior.
> 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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