peter-toth commented on PR #55885:
URL: https://github.com/apache/spark/pull/55885#issuecomment-5760079728

   @metanil a heads-up on sunchao's [P1 about the raw partition-key equality 
fast path](https://github.com/apache/spark/pull/55885#discussion_r3679486000): 
it is not specific to this PR.
   
   The same hole is live on master, through the identity-versus-transform arm 
SPARK-56182 added. A table partitioned by `identity(id)`, joined with one 
partitioned by a transform that reorders its key space, where both sides report 
the key list `[0, 1]`: the join returns 0 rows instead of 2, with no shuffle 
and no `GroupPartitionsExec` in the plan. I measured that on master and filed 
SPARK-59688, with the fix in #58943. `KeyedShuffleSpec.isCompatibleWith` there 
asks `areKeysCompatible` with `allowReduce = false`, so a pair whose keys still 
need reducing onto one key space is no longer read as lined up, and the join 
takes the push branch that reduces and regroups.
   
   So there is nothing for you to do here about that P1. Once #58943 lands it 
falls away on your rebase, and the gate widening in this PR inherits the fix.
   


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