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It is usual on databases to give the count where the column is non null. But if you

count(1)

or

count(*)

you will get the true row count.

I suspect count(column_x) might not include nulls, maybe depending on the useDefaultValueForNull setting. If you count(1) where column_x is null, does that and the other count add up to count(1)?

+1 ... count() in general does not count nulls (along with some of the other agg functions), so if you are counting a specific column or expression and it evaluates to null then it should not be counted. However, that assumes you are operating in SQL Null handling mode, e.g.

druid.generic.useDefaultValueForNull=false

I imagine if you are not in this mode then you will be defaulting your NULLs and your two counts would be the same.

okay thanks