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From 陶 加涛 <>
Subject About introduce function sum0 to Spark
Date Tue, 23 Oct 2018 02:39:33 GMT
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.

Aron Tao

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