[
https://issues.apache.org/jira/browse/FLINK-4469?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15671937#comment-15671937
]
ASF GitHub Bot commented on FLINK-4469:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/2653#discussion_r88337239
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/plan/logical/call.scala
---
@@ -0,0 +1,169 @@
+/*
+ * 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.api.table.plan.logical
+
+import java.lang.reflect.Method
+
+import org.apache.calcite.rel.logical.LogicalTableFunctionScan
+import org.apache.calcite.tools.RelBuilder
+import org.apache.flink.api.common.typeinfo.TypeInformation
+import org.apache.flink.api.table.{FlinkTypeFactory, TableEnvironment,
TableException, UnresolvedException}
+import org.apache.flink.api.table.expressions.{Attribute, Expression,
ResolvedFieldReference, UnresolvedFieldReference}
+import org.apache.flink.api.table.functions.TableFunction
+import org.apache.flink.api.table.functions.utils.TableSqlFunction
+import
org.apache.flink.api.table.functions.utils.UserDefinedFunctionUtils._
+import org.apache.flink.api.table.plan.schema.FlinkTableFunctionImpl
+import org.apache.flink.api.table.validate.ValidationFailure
+
+import scala.collection.JavaConversions._
+
+/**
+ * General expression for unresolved user-defined table function calls.
+ */
+case class UnresolvedTableFunctionCall(functionName: String, args:
Seq[Expression])
+ extends LogicalNode {
+
+ override def output: Seq[Attribute] =
+ throw UnresolvedException("Invalid call to output on
UnresolvedTableFunctionCall")
+
+ override protected[logical] def construct(relBuilder: RelBuilder):
RelBuilder =
+ throw UnresolvedException("Invalid call to construct on
UnresolvedTableFunctionCall")
+
+ override private[flink] def children: Seq[LogicalNode] =
+ throw UnresolvedException("Invalid call to children on
UnresolvedTableFunctionCall")
+}
+
+/**
+ * LogicalNode for calling a user-defined table functions.
+ * @param tableFunction table function to be called (might be overloaded)
+ * @param parameters actual parameters
+ * @param alias output fields renaming
+ * @tparam T type of returned table
+ */
+case class TableFunctionCall[T: TypeInformation](
+ tableFunction: TableFunction[T],
+ parameters: Seq[Expression],
+ alias: Option[Array[String]]) extends UnaryNode {
+
+ private var table: LogicalNode = _
+ override def child: LogicalNode = table
+
+ def setChild(child: LogicalNode): TableFunctionCall[T] = {
+ table = child
+ this
+ }
+
+ private val resultType: TypeInformation[T] =
+ if (tableFunction.getResultType == null) {
+ implicitly[TypeInformation[T]]
+ } else {
+ tableFunction.getResultType
+ }
+
+ private val fieldNames: Array[String] =
+ if (alias.isEmpty) {
+ getFieldAttribute[T](resultType)._1
+ } else {
+ alias.get
+ }
+ private val fieldTypes: Array[TypeInformation[_]] =
getFieldAttribute[T](resultType)._2
+
+ /**
+ * Assigns an alias for this table function returned fields that the
following `select()` clause
+ * can refer to.
+ *
+ * @param aliasList alias for this window
+ * @return this table function
+ */
+ def as(aliasList: Expression*): TableFunctionCall[T] = {
+ if (aliasList == null) {
+ return this
+ }
+ if (aliasList.length != fieldNames.length) {
+ failValidation("Aliasing not match number of fields")
+ } else if
(!aliasList.forall(_.isInstanceOf[UnresolvedFieldReference])) {
+ failValidation("Alias only accept name expressions as arguments")
+ } else {
+ val names =
aliasList.map(_.asInstanceOf[UnresolvedFieldReference].name).toArray
+ TableFunctionCall(tableFunction, parameters, Some(names))
+ }
+ }
+
+ override def output: Seq[Attribute] = fieldNames.zip(fieldTypes).map {
+ case (n, t) => ResolvedFieldReference(n, t)
+ }
+
+ override def makeCopy(newArgs: Array[AnyRef]): TableFunctionCall[T] = {
+ if (newArgs.length != 3) {
+ throw new TableException("Invalid constructor params")
+ }
+ val udtfParam: TableFunction[T] =
newArgs.head.asInstanceOf[TableFunction[T]]
+ val expressionParams = newArgs(1).asInstanceOf[Seq[Expression]]
+ val names = newArgs.last.asInstanceOf[Option[Array[String]]]
+ copy(udtfParam, expressionParams, names)
+ .asInstanceOf[TableFunctionCall[T]].setChild(child)
+ }
+
+ private var evalMethod: Method = _
+
+ override def validate(tableEnv: TableEnvironment): LogicalNode = {
+ val node = super.validate(tableEnv).asInstanceOf[TableFunctionCall[T]]
+ val signature = node.parameters.map(_.resultType)
+ // look for a signature that matches the input types
+ val foundMethod = getEvalMethod(tableFunction, signature)
+ if (foundMethod.isEmpty) {
+ ValidationFailure(s"Given parameters do not match any signature. \n"
+
+ s"Actual: ${signatureToString(signature)} \n" +
--- End diff --
I think `signatureToString` does not include the name of the function.
Would be good to add this to the exception message to help the user identify
the problem.
> Add support for user defined table function in Table API & SQL
> --------------------------------------------------------------
>
> Key: FLINK-4469
> URL: https://issues.apache.org/jira/browse/FLINK-4469
> Project: Flink
> Issue Type: New Feature
> Components: Table API & SQL
> Reporter: Jark Wu
> Assignee: Jark Wu
>
> Normal user-defined functions, such as concat(), take in a single input row
> and output a single output row. In contrast, table-generating functions
> transform a single input row to multiple output rows. It is very useful in
> some cases, such as look up in HBase by rowkey and return one or more rows.
> Adding a user defined table function should:
> 1. inherit from UDTF class with specific generic type T
> 2. define one or more evel function.
> NOTE:
> 1. the eval method must be public and non-static.
> 2. the generic type T is the row type returned by table function. Because of
> Java type erasure, we can’t extract T from the Iterable.
> 3. use {{collect(T)}} to emit table row
> 4. eval method can be overload. Blink will choose the best match eval method
> to call according to parameter types and number.
> {code}
> public class Word {
> public String word;
> public Integer length;
> }
> public class SplitStringUDTF extends UDTF<Word> {
> public Iterable<Word> eval(String str) {
> if (str != null) {
> for (String s : str.split(",")) {
> collect(new Word(s, s.length()));
> }
> }
> }
> }
> // in SQL
> tableEnv.registerFunction("split", new SplitStringUDTF())
> tableEnv.sql("SELECT a, b, t.* FROM MyTable, LATERAL TABLE(split(c)) AS
> t(w,l)")
> // in Java Table API
> tableEnv.registerFunction("split", new SplitStringUDTF())
> // rename split table columns to “w” and “l”
> table.crossApply("split(c) as (w, l)")
> .select("a, b, w, l")
> // without renaming, we will use the origin field names in the POJO/case/...
> table.crossApply("split(c)")
> .select("a, b, word, length")
> // in Scala Table API
> val split = new SplitStringUDTF()
> table.crossApply(split('c) as ('w, 'l))
> .select('a, 'b, 'w, 'l)
> // outerApply for outer join to a UDTF
> table.outerApply(split('c))
> .select('a, 'b, 'word, 'length)
> {code}
> See [1] for more information about UDTF design.
> [1]
> https://docs.google.com/document/d/15iVc1781dxYWm3loVQlESYvMAxEzbbuVFPZWBYuY1Ek/edit#
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