I get it, thanks!
> 在 2015年12月31日，上午3:00，Michael Armbrust <[email protected]> 写道：
>
> The goal here is to ensure that the non-deterministic value is evaluated only
> once, so the result won't change for a given row (i.e. when sorting).
>
> On Tue, Dec 29, 2015 at 10:57 PM, 汪洋 <[email protected]
> <mailto:[email protected]>> wrote:
> Hi fellas,
> I am new to spark and I have a newbie question. I am currently reading the
> source code in spark sql catalyst analyzer. I not quite understand the
> partial function in PullOutNondeterministric. What does it mean by "pull
> out”? Why do we have to do the "pulling out”?
> I would really appreciate it if somebody explain it to me.
> Thanks.
>
