Cheappie commented on issue #4533:
URL: 
https://github.com/apache/arrow-datafusion/issues/4533#issuecomment-1351339352

   >>> What do you think about moving schema inference into scan and removing 
it from TableProvider trait ?
   
   >> I don't think this is possible, as planning needs to know the schema. In 
general though performing schema inference per query is very expensive, 
especially for non-parquet data. I strongly recommend investing in some sort of 
catalog to store this data.
   
   > I thought that maybe schema could be kept(cached) in TableProvider 
implementations but It would be exposed only through scan operation. For 
example FileScanConfig holds a reference to the schema. Sure It could be solved 
differently, but in my case schema inference is not as bad as It would seem to 
be.
   
   bump, what do you think ? In such case, schema inference would be a detail 
of scan operation, It could be inferred ahead of time or on every query. 


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