Rafferty97 commented on issue #12852:
URL: https://github.com/apache/datafusion/issues/12852#issuecomment-2469474930

   Having thought about it some more, I think the use of `Schema::try_merge` is 
actually incorrect for CSV files, because the CSV reading process assumes that 
the fields in the `Schema` are in the same order as they appear in the file.
   
   So, if two CSVs are read in with the same columns but out of order, this 
will cause data to appear in the wrong columns. This might error out if there 
is a mismatch in types, but could also just silently return bogus data.
   
   My intuition is that the code needs to be changed to merge CSV schemas based 
on field index not field name.


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