[GitHub] [arrow-datafusion] mustafasrepo commented on pull request #5912: [Minor] Cleanup `SumAccumulator`

["mustafasrepo (via GitHub)" <gi...@apache.org>]

mustafasrepo commented on PR #5912:
URL: https://github.com/apache/arrow-datafusion/pull/5912#issuecomment-1500343987

   Thanks @Dandandan for this PR. As fas as I know, `count` stores the element number in the sum. When count is 0, we should produce `NULL`. Consider expression `SUM(inc_col) OVER(ORDER BY ts ASC ROWS BETWEEN 2 FOLLOWING AND 3 FOLLOWING) as sum1` for the last 2 results we should produce `NULL`. However, without storing count, we cannot differentiate `NULL`, and `0`. In the failing test, this can be seen also. (Executor produces 0, where it should have been produced `NULL`)
   
   Maybe there is way to accomplish this without storing count. I just wanted to mention, current use of it.


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