based on what I can see in

AvgAggregationFunction.java

it looks as though null handling is implemented, but it seems that

avg

is still including nulls in the count (where avg is implemented as sum/count). I confirmed this using filtering, and test data where there are only 2 rows like this:

myCol  
 ------- 
     1      
  null

No filtering:

SELECT avg(myCol) from myTable

results in

0.5

With filtering:

SELECT avg(myCol) from myTableWHERE myCol is not null

results in

1

Is this expected? Looks like a bug to me.