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https://issues.apache.org/jira/browse/FLINK-6232?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16073739#comment-16073739
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ASF GitHub Bot commented on FLINK-6232:
---------------------------------------

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

    https://github.com/apache/flink/pull/3715#discussion_r125459202
  
    --- Diff: 
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/join/WindowJoinUtil.scala
 ---
    @@ -300,22 +271,27 @@ object JoinUtil {
           }
         }
     
    -    val literalRex = replaceTimeFieldWithLiteral(rexNode)
    +    val literalLeftRex = replaceTimeFieldWithLiteral(leftRexNode)
    +    val literalRightRex = replaceTimeFieldWithLiteral(rightRexNode)
     
         val exprReducer = new ExpressionReducer(config)
         val originList = new util.ArrayList[RexNode]()
    -    originList.add(literalRex)
    +    originList.add(literalLeftRex)
    +    originList.add(literalRightRex)
         val reduceList = new util.ArrayList[RexNode]()
         exprReducer.reduce(rexBuilder, originList, reduceList)
     
    -    reduceList.get(0) match {
    +    val literals = reduceList.map(f => f match {
           case call: RexCall =>
    --- End diff --
    
    Which case is this? 
    Isn't a blind cast of the first operand to `RexLiteral` dangerous and could 
result in a `ClassCastException`?


> Support proctime inner equi-join between two streams in the SQL API
> -------------------------------------------------------------------
>
>                 Key: FLINK-6232
>                 URL: https://issues.apache.org/jira/browse/FLINK-6232
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Table API & SQL
>            Reporter: hongyuhong
>            Assignee: hongyuhong
>
> The goal of this issue is to add support for inner equi-join on proc time 
> streams to the SQL interface.
> Queries similar to the following should be supported:
> {code}
> SELECT o.proctime, o.productId, o.orderId, s.proctime AS shipTime 
> FROM Orders AS o 
> JOIN Shipments AS s 
> ON o.orderId = s.orderId 
> AND o.proctime BETWEEN s.proctime AND s.proctime + INTERVAL '1' HOUR;
> {code}
> The following restrictions should initially apply:
> * The join hint only support inner join
> * The ON clause should include equi-join condition
> * The time-condition {{o.proctime BETWEEN s.proctime AND s.proctime + 
> INTERVAL '1' HOUR}} only can use proctime that is a system attribute, the 
> time condition only support bounded time range like {{o.proctime BETWEEN 
> s.proctime - INTERVAL '1' HOUR AND s.proctime + INTERVAL '1' HOUR}}, not 
> support unbounded like {{o.proctime > s.protime}},  and  should include both 
> two stream's proctime attribute, {{o.proctime between proctime() and 
> proctime() + 1}} should also not be supported.
> This issue includes:
> * Design of the DataStream operator to deal with stream join
> * Translation from Calcite's RelNode representation (LogicalJoin). 



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