That's a horrible name. This is just a fold. On Mon, Oct 22, 2018 at 7:39 PM 陶 加涛 <taojia...@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 > > >
