alamb commented on issue #9011:
URL: 
https://github.com/apache/arrow-datafusion/issues/9011#issuecomment-1914569503

   I am not sure what is going on here. 
   
   Could it be that the `Pivot`/`Unpivot` operations somehow are configured to 
preserve all the columns (and thus the optimizer wouldn't be able to remove 
their use). This would be if the output of `Pivot::expressions()` refered to 
all the columns. Maybe we should extend their display to show what expressions 
are being used 
   
   One thing that might help debug here, depending on how you are invoking the 
optimzer, is to look at how DataFusion uses this
   
   
https://github.com/apache/arrow-datafusion/blob/1097dc0345079e81ba217ef23fd408a5c13c3d6c/datafusion/core/src/physical_optimizer/output_requirements.rs#L91
   
   When it is optimizing internally, it uses `OutputRequirementExec` to 
describe what properties are needed at the output
   
   


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