[jira] [Created] (SPARK-45507) Correctness bug in correlated scalar subqueries with COUNT aggregates

["Andy Lam (Jira)" <ji...@apache.org>]

Andy Lam created SPARK-45507:
--------------------------------

             Summary: Correctness bug in correlated scalar subqueries with COUNT aggregates
                 Key: SPARK-45507
                 URL: https://issues.apache.org/jira/browse/SPARK-45507
             Project: Spark
          Issue Type: Bug
          Components: SQL
    Affects Versions: 4.0.0
            Reporter: Andy Lam


{code:java}
 
create view if not exists t1(a1, a2) as values (0, 1), (1, 2);
create view if not exists t2(b1, b2) as values (0, 2), (0, 3);
create view if not exists t3(c1, c2) as values (0, 2), (0, 3);

-- Example 1 (has having clause)
select (
  select SUM(l.cnt + r.cnt)
  from (select count(*) cnt from t2 where t1.a1 = t2.b1 having cnt = 0) l
  join (select count(*) cnt from t3 where t1.a1 = t3.c1 having cnt = 0) r
  on l.cnt = r.cnt
) from t1

-- Correct answer: (null, 0)
+----------------------+
|scalarsubquery(c1, c1)|
+----------------------+
|null                  |
|null                  |
+----------------------+

-- Example 2
select ( select sum(cnt) from (select count(*) cnt from t2 where t1.c1 = t2.c1) ) from t1

-- Correct answer: (2, 0)
+------------------+
|scalarsubquery(c1)|
+------------------+
|2                 |
|null              |
+------------------+

-- Example 3
select ( select count(*) from (select count(*) cnt from t2 where t1.c1 = t2.c1) ) from t1

-- Correct answer: (1, 1)
+------------------+
|scalarsubquery(c1)|
+------------------+
|1                 |
|0                 |
+------------------+ {code}
 

 

DB fiddle for correctness check:[https://www.db-fiddle.com/f/4jyoMCicNSZpjMt4jFYoz5/10403#]



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