[jira] [Created] (DRILL-2411) Scalar SUM/AVG over empty result set returns no rows instead of NULL

["Victoria Markman (JIRA)" <ji...@apache.org>]

Victoria Markman created DRILL-2411:
---------------------------------------

             Summary: Scalar SUM/AVG over empty result set returns no rows instead of NULL
                 Key: DRILL-2411
                 URL: https://issues.apache.org/jira/browse/DRILL-2411
             Project: Apache Drill
          Issue Type: Bug
          Components: Query Planning & Optimization
            Reporter: Victoria Markman
            Assignee: Jinfeng Ni


Queries below should return NULL:
{code}
0: jdbc:drill:schema=dfs> select sum(a2) from t2 where 1=0;
+------------+
|   EXPR$0   |
+------------+
+------------+
No rows selected (0.08 seconds)

0: jdbc:drill:schema=dfs> select avg(a2) from t2 where 1=0;
+------------+
|   EXPR$0   |
+------------+
+------------+
No rows selected (0.074 seconds)
{code}

When grouped, result is correct:
{code}
0: jdbc:drill:schema=dfs> select a2, sum(a2) from t2 where 1=0 group by a2;
+------------+------------+
|     a2     |   EXPR$1   |
+------------+------------+
+------------+------------+
No rows selected (0.11 seconds)
{code}

I'm not convinced and it is not very intuitive that correct result should be NULL, but this is what postgres returns and Aman thinks NULL is the correct behavior :)



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