alexeykudinkin commented on issue #5519:
URL: https://github.com/apache/hudi/issues/5519#issuecomment-1307831723

   Folks, this is unfortunately an issue not of Hudi itself, but rather w/in 
both Parquet and Spark: as part of holistically addressing issues of handling 
schemas in Hudi in https://github.com/apache/hudi/pull/6358, i've stumbled upon 
this issue as well and here are my findings:
   
    - Type promotions could only work properly (in Spark/Parquet env) in case 
you're overwriting all of your data-files. In case you have a heterogeneous env 
where you have both base files in old schema and the new schema you'll be 
having issues reading such table (see below)
    - Heterogeneous table w/ type promotions won't work w/ Parquet when 
Dictionary Encoding is enabled (requires fixing DE impl in Parquet)
    - Heterogeneous table w/ type promotions won't work w/ Spark Vectorized 
Reader either 
([SPARK-40876](https://issues.apache.org/jira/projects/SPARK/issues/SPARK-40876?filter=allopenissues))
   
   As such, there's no way this could be reliably supported w/in Hudi 
currently. Closing this for now.


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