Github user nsyca commented on a diff in the pull request:
https://github.com/apache/spark/pull/17186#discussion_r106166444
--- Diff:
sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/PruneFiltersSuite.scala
---
@@ -133,4 +146,28 @@ class PruneFiltersSuite extends PlanTest {
val correctAnswer = testRelation.where(Rand(10) > 5).where(Rand(10) >
5).select('a).analyze
comparePlans(optimized, correctAnswer)
}
+
+ test("No pruning when constraint propagation is disabled") {
+ val tr1 = LocalRelation('a.int, 'b.int, 'c.int).subquery('tr1)
+ val tr2 = LocalRelation('a.int, 'd.int, 'e.int).subquery('tr2)
+
+ val query = tr1
+ .where("tr1.a".attr > 10 || "tr1.c".attr < 10)
+ .join(tr2.where('d.attr < 100), Inner, Some("tr1.a".attr ===
"tr2.a".attr))
+
+ val queryWithUselessFilter =
+ query.where(
+ ("tr1.a".attr > 10 || "tr1.c".attr < 10) &&
+ 'd.attr < 100)
+
+ val optimized =
OptimizeDisableConstraintPropagation.execute(queryWithUselessFilter.analyze)
+ // When constraint propagation is disabled, the useless filter won't
be pruned.
+ // It gets pushed down. Because the rule `CombineFilters` runs only
once, there are redundant
+ // and duplicate filters.
--- End diff --
This behaviour does not make sense to me. If I write a query like
`select * from (select * from t1 where t1.a1 > 1) tx where tx.a1 > 1`
I expect that Spark evaluates the predicate only once. The wording of
"constraint propagation" is misleading. In this example, there is no activity
of propagation at all. Perhaps we want to distinguish the "constraints" between
the ones written originally and the ones that are inferred from relationships
with other predicates. When the "propagation" (or perhaps a more meaningful
term "predicate inference") is set to OFF, we want to exclude those inferred
predicates in the `def constraints`.
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