alamb commented on issue #3463:
URL: https://github.com/apache/datafusion/issues/3463#issuecomment-3712034479

   > Oh right, yes it will do that sorry, been years since I wrote that code 
(and it looks like there's some new PushDecoder anyway that might change all of 
this). 
   
   FWIW the push decoder doesn't change the fundamental IO -- it is instead an 
explicit state machine (rather than using the implicit one created by the rust 
compiler with `await` calls). It is algorithmically the same thing 
   
   > So yes it will behave the way you describe, which could make a difference 
for stores with high first-byte latencies. However, my understanding is Andrew 
is running on an NVMe drive where time spent doing IO will be bounded by 
bytes-read not number of fetches, which filter pushdown would if anything 
reduce...
   
   The idea that one reason it slows down is due to additional latency of 
multiple distinct IOs is an interesting one. I will ponder that and see if I 
can find some way to reduce it / prefetch


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