maryannxue opened a new pull request #23524: [FOLLOW-UP][SPARK-26065][SQL] Fix 
the Failure when having two Consecutive Hints
URL: https://github.com/apache/spark/pull/23524
 
 
   ## What changes were proposed in this pull request?
   
   This is to fix a bug in #23036 that would cause a join hint to be applied on 
node it is not supposed to after join reordering. For example,
   ```
     val join = df.join(df, "id")
     val broadcasted = join.hint("broadcast")
     val join2 = join.join(broadcasted, "id").join(broadcasted, "id")
   ```
   There should only be 2 broadcast hints on `join2`, but after join reordering 
there would be 4. It is because the hint application in join reordering 
compares the attribute set for testing relation equivalency.
   Moreover, it could still be problematic even if the child relations were 
used in testing relation equivalency, due to the potential exprId conflict in 
nested self-join. 
   
   As a result, this PR simply reverts the join reorder hint behavior change 
introduced in #23036, which means if a join hint is present, the join node 
itself will not participate in the join reordering, while the sub-joins within 
its children still can.
   
   ## How was this patch tested?
   
   Added new tests
   

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