Enrico Minack created SPARK-41162:
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Summary: Anti-join must not be pushed below aggregation with
ambiguous predicates
Key: SPARK-41162
URL: https://issues.apache.org/jira/browse/SPARK-41162
Project: Spark
Issue Type: Bug
Components: SQL
Affects Versions: 3.4.0
Reporter: Enrico Minack
The following query should return a single row as all values for `id` except
for the largest will be eliminated by the anti-join:
{code}
val ids = Seq(1, 2, 3).toDF("id").distinct()
val result = ids.withColumn("id", $"id" + 1).join(ids, "id",
"left_anti").collect()
assert(result.length == 1)
{code}
Without the {{distinct()}}, the assertion is true. With {{distinct()}}, the
assertion should still hold but is false.
Rule {{PushDownLeftSemiAntiJoin}} pushes the {{Join}} below the left
{{Aggregate}} with join condition {{(id#750 + 1) = id#750}}, which can never be
true.
{code}
=== Applying Rule
org.apache.spark.sql.catalyst.optimizer.PushDownLeftSemiAntiJoin ===
!Join LeftAnti, (id#752 = id#750) 'Aggregate [id#750],
[(id#750 + 1) AS id#752]
!:- Aggregate [id#750], [(id#750 + 1) AS id#752] +- 'Join LeftAnti, ((id#750
+ 1) = id#750)
!: +- LocalRelation [id#750] :- LocalRelation [id#750]
!+- Aggregate [id#750], [id#750] +- Aggregate [id#750],
[id#750]
! +- LocalRelation [id#750] +- LocalRelation
[id#750]
{code}
The optimizer then rightly removes the left-anti join altogether, returning the
left child only.
Rule {{PushDownLeftSemiAntiJoin}} should not push down predicates that
reference left *and* right child.
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