Allison Wang created SPARK-35080:
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Summary: Correlated subqueries with equality predicates can return
wrong results
Key: SPARK-35080
URL: https://issues.apache.org/jira/browse/SPARK-35080
Project: Spark
Issue Type: Bug
Components: SQL
Affects Versions: 3.2.0
Reporter: Allison Wang
Correlated subqueries with aggregate can return wrong results even with
correlated equality predicates. Currently, the decorrelation framework does not
support these types of correlated subqueries, and they should be blocked in
CheckAnalysis.
Example 1:
{code:sql}
create or replace view t1(c) as values ('a'), ('b')
create or replace view t2(c) as values ('ab'), ('abc'), ('bc')
select c, (select count(*) from t2 where t1.c = substring(t2.c, 1, 1)) from t1
{code}
Correct results: [(a, 2), (b, 1)]
Spark results:
{code:java}
+---+-----------------+
|c |scalarsubquery(c)|
+---+-----------------+
|a |1 |
|a |1 |
|b |1 |
+---+-----------------+{code}
Example 2:
{code:sql}
create or replace view t1(a, b) as values (0, 6), (1, 5), (2, 4), (3, 3);
create or replace view t2(c) as values (6);
select c, (select count(*) from t1 where a + b = c) from t2;{code}
Correct results: [(6, 4)]
Spark results:
{code:java}
+---+-----------------+
|c |scalarsubquery(c)|
+---+-----------------+
|6 |1 |
|6 |1 |
|6 |1 |
|6 |1 |
+---+-----------------+
{code}
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