[GitHub] [iceberg] kbendick commented on issue #4849: Ignore downcasting of column types when "mergeSchema" is set.

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kbendick commented on issue #4849:
URL: https://github.com/apache/iceberg/issues/4849#issuecomment-1138192430

   Thanks for reporting this @schatterjee10.
   
   I’d be open to a quick demo PR, but I do worry about trying to be very “smart” with casting rules. We do allow for “incompatible” schema updates to be made, but this would require casting the data afaik and `mergeSchema` should really err on the side of caution in my opinion.
   
   That said, if you have a sample draft POC to show this is possible, I think we’d be willing to take a look to consider it. Again though, to be really correct the data should be stored in the files as long (in my opinion) and should likely be casted.
   
   But I will admit I’m not super familiar with this code so if it can be easily resolved, feel free to present it or discuss it. But in general, I’m hesitant about overriding the built in rules about dangerous casting. Eventually, I worry it will come back to bite us.
   
   I’m just one person so others might disagree, but that’s my 2 cents fwiw. 


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