zhuqi-lucas commented on code in PR #14245:
URL: https://github.com/apache/datafusion/pull/14245#discussion_r1929438149


##########
datafusion/sqllogictest/test_files/joins.slt:
##########
@@ -4247,8 +4247,10 @@ logical_plan
 physical_plan
 01)CoalesceBatchesExec: target_batch_size=3, fetch=2
 02)--HashJoinExec: mode=CollectLeft, join_type=Full, on=[(c1@0, c1@0)]
-03)----MemoryExec: partitions=1, partition_sizes=[1]
-04)----MemoryExec: partitions=1, partition_sizes=[1]
+03)----GlobalLimitExec: skip=0, fetch=2

Review Comment:
   Thank you @alamb for review, actually we don't do anything for the full join 
limit in this PR.
   
   
   **The logical plan already push down full join limit since:**
   [#12963](https://github.com/apache/datafusion/pull/12963)
   
   For example the following code:
   ```
   ## Test !join.on.is_empty() && join.filter.is_none()
   query TT
   EXPLAIN SELECT * FROM t0 FULL JOIN t1 ON t0.c1 = t1.c1 LIMIT 2;
   ----
   logical_plan
   01)Limit: skip=0, fetch=2
   02)--Full Join: t0.c1 = t1.c1
   03)----Limit: skip=0, fetch=2
   04)------TableScan: t0 projection=[c1, c2], fetch=2
   05)----Limit: skip=0, fetch=2
   06)------TableScan: t1 projection=[c1, c2, c3], fetch=2
   ```
   
   
   And the physical plan will apply it, but before this PR, the child limit 
will be overridden by parent limit, so it does not the limit before for the 
case.
   
   I suggest we can create a following issue to discuss do we need to fallback 
or change the full join push down limit case:
   [#12963](https://github.com/apache/datafusion/pull/12963)
   
   What's your opinion? Thanks a lot!
   



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