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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-5256) Extend DataSetSingleRowJoin to support Left and Right joins
Date Wed, 10 May 2017 08:48:04 GMT

    [ https://issues.apache.org/jira/browse/FLINK-5256?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16004324#comment-16004324
] 

ASF GitHub Bot commented on FLINK-5256:
---------------------------------------

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

    https://github.com/apache/flink/pull/3673#discussion_r115685695
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/MapJoinLeftRunner.scala
---
    @@ -31,7 +32,19 @@ class MapJoinLeftRunner[IN1, IN2, OUT](
       override def flatMap(multiInput: IN1, out: Collector[OUT]): Unit = {
         broadcastSet match {
           case Some(singleInput) => function.join(multiInput, singleInput, out)
    -      case None =>
    +      case None => {
    --- End diff --
    
    Really, I cant imagine situation when there we will got null. Please see in /flink/flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/MapSideJoinRunner.scala
who is parent of these runners. 
    org/apache/flink/table/runtime/MapSideJoinRunner.scala:48
    `    broadcastSet = retrieveBroadcastSet
      }
    
      private def retrieveBroadcastSet: Option[SINGLE_IN] = {
        val broadcastSet = getRuntimeContext.getBroadcastVariable(broadcastSetName)
        if (!broadcastSet.isEmpty) {
          Option(broadcastSet.get(0))
        } else {
          Option.empty
        }
      }`


> Extend DataSetSingleRowJoin to support Left and Right joins
> -----------------------------------------------------------
>
>                 Key: FLINK-5256
>                 URL: https://issues.apache.org/jira/browse/FLINK-5256
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table API & SQL
>    Affects Versions: 1.2.0
>            Reporter: Fabian Hueske
>            Assignee: Dmytro Shkvyra
>
> The {{DataSetSingleRowJoin}} is a broadcast-map join that supports arbitrary inner joins
where one input is a single row.
> I found that Calcite translates certain subqueries into non-equi left and right joins
with single input. These cases can be handled if the  {{DataSetSingleRowJoin}} is extended
to support outer joins on the non-single-row input, i.e., left joins if the right side is
single input and vice versa.



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