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From Mark Hamstra <m...@clearstorydata.com>
Subject Re: About introduce function sum0 to Spark
Date Tue, 23 Oct 2018 04:28:02 GMT
That's a horrible name. This is just a fold.

On Mon, Oct 22, 2018 at 7:39 PM 陶 加涛 <taojiatao@gmail.com> wrote:

> Hi, in calcite, has the concept of sum0, here I quote the definition of
> sum0:
>
>
>
> Sum0 is an aggregator which returns the sum of the values which
>
> go into it like Sum. It differs in that when no non null values
>
> are applied zero is returned instead of null..
>
>
>
> One scenario is that we can use sum0 to implement pre-calculation
> count(pre-calculation system like Apache Kylin).
>
>
>
> It is very easy in Spark to implement sum0, if community consider this is
> necessary, I would like to open a JIRA and implement this.
>
>
>
> ---
>
> Regards!
>
> Aron Tao
>
>
>

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