[GitHub] flink pull request #4471: [FLINK-6094] [table] Implement stream-stream proct...

[xccui]

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

    https://github.com/apache/flink/pull/4471#discussion_r146104726
  
    --- Diff: 
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/util/UpdatingPlanChecker.scala
 ---
    @@ -56,16 +58,20 @@ object UpdatingPlanChecker {
       }
     
       /** Identifies unique key fields in the output of a RelNode. */
    -  private class UniqueKeyExtractor extends RelVisitor {
    +  private class UniqueKeyExtractor {
    --- End diff --
    
    Are these changes on `UniqueKeyExtractor` necessary? I'd suggest to make it 
a separate issue (and for inputs retraction as well).


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