Github user yanboliang commented on the issue:
https://github.com/apache/spark/pull/18902
@zhengruifeng DataFrame-based operation is 2~3x slower than RDD-based
operation is a known issue, because of the deserialization cost. If we switch
to RDD-based method, we need to implement our own aggregator to calculate
_mean_ and _median_, this need much more code than calling DataFrame API. BTW,
DF using more compact structure that can reduce memory footprint.
From my perspective, I'd suggest to keep the current DF-based solution. As
it will 5~10 faster than the original implementation. @hhbyyh @MLnick What do
you think about it? Thanks.
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