neilconway opened a new issue, #22743:
URL: https://github.com/apache/datafusion/issues/22743

   ### Describe the bug
   
   estimate_join_cardinality (datafusion/physical-plan/src/joins/utils.rs) 
estimates a reduced row count for semi/anti joins but returns the preserved 
input's column statistics unchanged. The per-column stats then describe the 
full input rather than the emitted subset:
   
   - null_count, distinct_count, and byte_size become inconsistent with the 
output num_rows (e.g. null_count > num_rows).
   - sum_value still reflects the full input.
   - Exact values are preserved even though a subset is only an estimate.
   - Join-key columns just copy the input null count, but null keys never match 
— a semi join drops them all, an anti join keeps them all.
   
   ### To Reproduce
   
   _No response_
   
   ### Expected behavior
   
   _No response_
   
   ### Additional context
   
   _No response_


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