parthchandra commented on PR #968:
URL: https://github.com/apache/parquet-mr/pull/968#issuecomment-1136552664

   > This is interesting, because when I did profiling of Trino, I found that 
although I/O (from S3, over the network no less) was significant, even more 
time was spent in compute. Maybe you're getting improved performance because 
you're increasing _parallelism_ between I/O and compute.
   
   It may be because I was using Spark's vectorized parquet decoding which is 
an order or magnitude faster than parquet library's row by row decoding (see 
[Spark 
benchmarks](https://github.com/apache/spark/blob/master/sql/core/benchmarks/DataSourceReadBenchmark-results.txt)).
 If trino is not doing vectorized decoding (I took a very quick look and I 
don't think it is), I would suggest you can look into that next. All the cool 
kids are doing it. 


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