alamb commented on issue #9111:
URL: 
https://github.com/apache/arrow-datafusion/issues/9111#issuecomment-1926784866

   > All expressions can be rewritten if a change occurs in the plan because of 
this kind of index changes.
   
   Right -- I think the difference is that in the Physical realm, projection 
pushdown could maintain the mapping of "is output column N used" where N is the 
index. 
   
   Then the trick will be to implement the transformation for each type of 
ExecutionPlan to both:
   1. Rewrite itself if one of its output columns is not used
   2. Describe which of the columns on the input are required to create its 
output
   
   With thse two functions I think you could implement a pretty simple pushdown 
rule


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