Jack Chen created SPARK-43098:
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Summary: Should not handle the COUNT bug when the GROUP BY clause
of a correlated scalar subquery is non-empty
Key: SPARK-43098
URL: https://issues.apache.org/jira/browse/SPARK-43098
Project: Spark
Issue Type: Sub-task
Components: SQL
Affects Versions: 3.2.0
Reporter: Jack Chen
>From [~allisonwang-db] :
There is no COUNT bug when the correlated equality predicates are also in the
group by clause. However, the current logic to handle the COUNT bug still adds
default aggregate function value and returns incorrect results.
{code:java}
create view t1(c1, c2) as values (0, 1), (1, 2);
create view t2(c1, c2) as values (0, 2), (0, 3);
select c1, c2, (select count(*) from t2 where t1.c1 = t2.c1 group by c1) from
t1;
-- Correct answer: [(0, 1, 2), (1, 2, null)]
+---+---+------------------+
|c1 |c2 |scalarsubquery(c1)|
+---+---+------------------+
|0 |1 |2 |
|1 |2 |0 |
+---+---+------------------+
{code}
This bug affects scalar subqueries in RewriteCorrelatedScalarSubquery, but
lateral subqueries handle it correctly in DecorrelateInnerQuery. Related:
https://issues.apache.org/jira/browse/SPARK-36113
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