Github user HyukjinKwon commented on a diff in the pull request:
https://github.com/apache/spark/pull/13155#discussion_r63626503
--- Diff: sql/core/src/test/scala/org/apache/spark/sql/SubquerySuite.scala
---
@@ -293,4 +293,65 @@ class SubquerySuite extends QueryTest with
SharedSQLContext {
""".stripMargin),
Row(3) :: Nil)
}
+
+ test("COUNT bug in WHERE clause (Filter)") {
+
+ // Case 1: Canonical example of the COUNT bug
+ checkAnswer(
+ sql("select l.a from l where (select count(*) from r where l.a =
r.c) < l.a"),
+ Row(1) :: Row(1) :: Row(3) :: Row(6) :: Nil)
+
+ // Case 2: count(*) = 0; could be rewritten to NOT EXISTS but
currently uses
+ // a rewrite that is vulnerable to the COUNT bug
+ checkAnswer(
+ sql("select l.a from l where (select count(*) from r where l.a =
r.c) = 0"),
+ Row(1) :: Row(1) :: Row(null) :: Row(null) :: Nil)
+
+ // Case 3: COUNT bug without a COUNT aggregate
+ checkAnswer(
+ sql("select l.a from l where (select sum(r.d) is null from r where
l.a = r.c)"),
+ Row(1) :: Row(1) ::Row(null) :: Row(null) :: Row(6) :: Nil)
+
+ }
+
+ test("COUNT bug in SELECT clause (Project)") {
+ checkAnswer(
+ sql("select a, (select count(*) from r where l.a = r.c) as cnt from
l"),
+ Row(1, 0) :: Row(1, 0) :: Row(2, 2) :: Row(2, 2) :: Row(3, 1) ::
Row(null, 0)
+ :: Row(null, 0) :: Row(6, 1) :: Nil)
+ }
+
+ test("COUNT bug in HAVING clause (Filter)") {
+ checkAnswer(
+ sql("select l.a as grp_a from l group by l.a " +
+ "having (select count(*) from r where grp_a = r.c) = 0 " +
+ "order by grp_a"),
+ Row(null) :: Row(1) :: Nil)
+ }
+
+ test("COUNT bug in Aggregate") {
+ checkAnswer(
+ sql("select l.a as aval, sum((select count(*) from r where l.a =
r.c)) as cnt " +
+ "from l group by l.a order by aval"),
+ Row(null, 0) :: Row(1, 0) :: Row(2, 4) :: Row(3, 1) :: Row(6, 1) ::
Nil)
+ }
+
+ test("COUNT bug negative examples") {
+ // Case 1: Potential COUNT bug case that was working correctly prior
to the fix
+ checkAnswer(
+ sql("select l.a from l where (select sum(r.d) from r where l.a =
r.c) is null"),
+ Row(1) :: Row(1) :: Row(null) :: Row(null) :: Row(6) :: Nil)
+
+ // Case 2: COUNT aggregate but no COUNT bug due to > 0 test.
+ checkAnswer(
+ sql("select l.a from l where (select count(*) from r where l.a =
r.c) > 0"),
+ Row(2) :: Row(2) :: Row(3) :: Row(6) :: Nil)
+
+ // Case 3: COUNT inside aggregate expression but no COUNT bug.
+ checkAnswer(
+ sql("select l.a from l where (select count(*) + sum(r.d) from r
where l.a = r.c) = 0"),
+ Nil)
+
+
--- End diff --
(Maybe here too..)
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