Raviston6296 commented on issue #59434:
URL: https://github.com/apache/spark/issues/59434#issuecomment-6570979658

   This is the same root cause as SPARK-57956 (#57347): during AQE 
re-optimization, `LogicalQueryStage.maxRows` used a cost estimate of a 
not-yet-materialized stage as a hard upper bound, so `EliminateLimits` could 
drop a LIMIT. That fix is in `master`, `branch-4.x` and `branch-4.3`, but not 
in `branch-4.2` or `branch-4.1`.
   
   I reproduced the query from this issue on `branch-4.2` and `branch-4.1` 
(RDD-backed tables, `local[1]`, `spark.sql.shuffle.partitions=2`, 200 runs with 
AQE on): 19 and 18 runs returned 5 rows. With SPARK-57956 backported, all 200 
runs return 3 rows on both branches. Current master also returns 3 rows in 
every run.
   
   Backports: #60017 (`branch-4.2`) and #60018 (`branch-4.1`).
   


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