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https://issues.apache.org/jira/browse/FLINK-3850?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15902062#comment-15902062
 ] 

ASF GitHub Bot commented on FLINK-3850:
---------------------------------------

Github user fhueske commented on a diff in the pull request:

    https://github.com/apache/flink/pull/3040#discussion_r105032956
  
    --- Diff: 
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/nodes/dataset/forwarding/FieldForwardingUtils.scala
 ---
    @@ -0,0 +1,143 @@
    +/*
    + * 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.nodes.dataset.forwarding
    +
    +import org.apache.flink.api.common.typeinfo.{BasicArrayTypeInfo, 
BasicTypeInfo, TypeInformation => TypeInfo}
    +import org.apache.flink.api.common.typeutils.CompositeType
    +import org.apache.flink.api.java.DataSet
    +import org.apache.flink.table.api.TableException
    +import org.apache.flink.types.Row
    +
    +object FieldForwardingUtils {
    +
    +  def compositeTypeField = (fields: Seq[(String, TypeInfo[_])]) => fields
    --- End diff --
    
    This function can be removed, right?


> Add forward field annotations to DataSet operators generated by the Table API
> -----------------------------------------------------------------------------
>
>                 Key: FLINK-3850
>                 URL: https://issues.apache.org/jira/browse/FLINK-3850
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table API & SQL
>            Reporter: Fabian Hueske
>            Assignee: Nikolay Vasilishin
>
> The DataSet API features semantic annotations [1] to hint the optimizer which 
> input fields an operator copies. This information is valuable for the 
> optimizer because it can infer that certain physical properties such as 
> partitioning or sorting are not destroyed by user functions and thus generate 
> more efficient execution plans.
> The Table API is built on top of the DataSet API and generates DataSet 
> programs and code for user-defined functions. Hence, it knows exactly which 
> fields are modified and which not. We should use this information to 
> automatically generate forward field annotations and attach them to the 
> operators. This can help to significantly improve the performance of certain 
> jobs.
> [1] 
> https://ci.apache.org/projects/flink/flink-docs-release-1.0/apis/batch/index.html#semantic-annotations



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