Apache Pinot

If for a table we have set `nullHandlingEnabled` as true, and we do distinct count on a column that has nulls, does it filter out the null values and only show count of non null distinct values ?

That would be difficult as we would have other aggregations in the same query which are not filtered.

I would assume we would be able to add a udf to handle the same as well ?

or should we change the way distinct count / all other aggregations work when null handling is enabled.

yes, but checking for null in the udf will make hurt performance. you can use defaultNullValue and filter it out on the client side

the problem is its not clear what should be the default behavior

we could potentially filter it out, but when it comes to aggregations like distinct count, we dont have a way to be certain if the aggregation counted the null/default value or not and might skew our metrics.