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https://issues.apache.org/jira/browse/FLINK-6196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15957213#comment-15957213
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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_r109931036
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/schema/FlinkTableFunction.scala
---
@@ -0,0 +1,55 @@
+/*
+ * 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, Type}
+import java.util
+
+import org.apache.calcite.rel.`type`.{RelDataType, RelDataTypeFactory}
+import org.apache.calcite.schema.TableFunction
+import org.apache.calcite.schema.impl.ReflectiveFunctionBase
+import org.apache.flink.api.common.typeinfo.TypeInformation
+import org.apache.flink.table.functions.{TableFunction => FlinkUDTF}
+
+/**
+ * This is heavily inspired by Calcite's
[[org.apache.calcite.schema.impl.TableFunctionImpl]].
+ * We need it in order to create a
[[org.apache.flink.table.functions.utils.TableSqlFunction]].
+ * The main difference is that we override the [[getResultType()]] and
[[getElementType()]].
+ *
+ * @param tableFunction The Table Function instance
+ * @param evalMethod The eval() method of the [[tableFunction]]
+ */
+abstract class FlinkTableFunction(
+ tableFunction: FlinkUDTF[_],
+ evalMethod: Method)
+ extends ReflectiveFunctionBase(evalMethod)
+ with TableFunction {
+
+ override def getElementType(arguments: util.List[AnyRef]): Type =
classOf[Array[Object]]
+
+ /**
+ * Returns the TypeInformation for internal usage, i.e. code generation.
+ */
+ def getResultType(arguments: util.List[AnyRef]): TypeInformation[_]
+
+ /**
+ * Returns the record type of the table function to integrate with
Calcite.
+ */
+ def getRowType(typeFactory: RelDataTypeFactory, arguments:
util.List[AnyRef]): RelDataType
--- End diff --
This is method is not overridden and I think it can be removed.
> 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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