adriangb commented on PR #17758:
URL: https://github.com/apache/datafusion/pull/17758#issuecomment-3376814844

   From my testing this works but doesn't seem to have much of a positive 
benefit (does not improve query performance). Maybe something is wrong with the 
implementation. But I think fundamentally the problem is that you want to go 
wide with IO but not really with other parts (e.g. CPU work applying filters in 
predicate pushdown), and this is a bit too high of a level for that. @alamb is 
working on changes to Parquet decoding which will allow prefetching at the byte 
range level, that sounds much more appropriate since we will be able to do 
IO-only prefetching. I will continue to do some investigations  but I am going 
to close this for now to keep the PR backlog down.


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