wangyum commented on PR #59027:
URL: https://github.com/apache/spark/pull/59027#issuecomment-6544954116

   Ran the staggered-overlap cases at ~250x scale (build ~200K-1M ranges, probe 
~2.5M-100M rows) as plain Spark SQL on a real distributed cluster, flag on vs 
off:
   
   - staggered 5% overlap (long): 2.4 min vs 2.4 min
   - staggered 90% overlap (long): 29 min vs 31 min (range join faster)
   - staggered 5% overlap (double): 2.7 min vs 2.3 min
   - staggered 90% overlap (double): 31 min vs 30 min
   
   The microbenchmark's 0.5X-0.6X/0.7X-0.8X ratios are measured in a single JVM 
process, where the join's own CPU cost is the whole story; at distributed 
scale, shuffle/I/O/task-scheduling overhead dominates and the slowdown is 
within noise. So documentation alone looks sufficient here -- I've reworded the 
first trade-off in the config doc to describe which key families are more 
exposed without citing fixed ratios, since those numbers don't hold once the 
workload runs on a real cluster and risk reading as a stronger guarantee than 
they are.
   


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