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Posted to reviews@spark.apache.org by "allisonwang-db (via GitHub)" <gi...@apache.org> on 2023/08/10 22:30:13 UTC
[GitHub] [spark] allisonwang-db commented on a diff in pull request #41301: [SPARK-43780][SQL] Support correlated references in join predicates
allisonwang-db commented on code in PR #41301:
URL: https://github.com/apache/spark/pull/41301#discussion_r1290738214
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala:
##########
@@ -4268,6 +4268,14 @@ object SQLConf {
.checkValue(_ >= 0, "The threshold of cached local relations must not be negative")
.createWithDefault(64 * 1024 * 1024)
+ val DECORRELATE_JOIN_PREDICATE_ENABLED =
+ buildConf("spark.sql.optimizer.decorrelateJoinPredicate.enabled")
+ .internal()
+ .doc("Decorrelate subqueries with correlated references in join predicates.")
+ .version("3.5.0")
Review Comment:
Should this be `4.0.0`?
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/DecorrelateInnerQuery.scala:
##########
@@ -804,18 +804,74 @@ object DecorrelateInnerQuery extends PredicateHelper {
(d.copy(child = newChild), joinCond, outerReferenceMap)
case j @ Join(left, right, joinType, condition, _) =>
- val outerReferences = collectOuterReferences(j.expressions)
- // Join condition containing outer references is not supported.
- assert(outerReferences.isEmpty, s"Correlated column is not allowed in join: $j")
- val newOuterReferences = parentOuterReferences ++ outerReferences
- val shouldPushToLeft = joinType match {
+ // Given 'condition', computes the tuple of
+ // (correlated, uncorrelated, equalityCond, predicates, equivalences).
+ // 'correlated' and 'uncorrelated' are the conjuncts with (resp. without)
+ // outer (correlated) references. Furthermore, correlated conjuncts are split
+ // into 'equalityCond' (those that are equalities) and all rest ('predicates').
+ // 'equivalences' track equivalent attributes given 'equalityCond'.
+ def splitCorrelatedPredicate(condition: Option[Expression],
+ isInnerJoin: Boolean,
+ shouldDecorrelatePredicates: Boolean):
+ (Seq[Expression], Seq[Expression], Seq[Expression],
+ Seq[Expression], AttributeMap[Attribute]) = {
Review Comment:
```suggestion
def splitCorrelatedPredicate(
condition: Option[Expression],
isInnerJoin: Boolean,
shouldDecorrelatePredicates: Boolean):
(Seq[Expression], Seq[Expression], Seq[Expression],
Seq[Expression], AttributeMap[Attribute]) = {
```
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/DecorrelateInnerQuery.scala:
##########
@@ -804,18 +804,67 @@ object DecorrelateInnerQuery extends PredicateHelper {
(d.copy(child = newChild), joinCond, outerReferenceMap)
case j @ Join(left, right, joinType, condition, _) =>
- val outerReferences = collectOuterReferences(j.expressions)
- // Join condition containing outer references is not supported.
- assert(outerReferences.isEmpty, s"Correlated column is not allowed in join: $j")
- val newOuterReferences = parentOuterReferences ++ outerReferences
- val shouldPushToLeft = joinType match {
+ def splitCorrelatedPredicate(condition: Option[Expression],
+ isInnerJoin: Boolean,
+ shouldDecorrelatePredicates: Boolean):
+ (Seq[Expression], Seq[Expression], Seq[Expression],
+ Seq[Expression], AttributeMap[Attribute]) = {
Review Comment:
Thanks for adding the comment! If possible, can we also include a minimal example in this comment?
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala:
##########
@@ -4268,6 +4268,14 @@ object SQLConf {
.checkValue(_ >= 0, "The threshold of cached local relations must not be negative")
.createWithDefault(64 * 1024 * 1024)
+ val DECORRELATE_JOIN_PREDICATE_ENABLED =
+ buildConf("spark.sql.optimizer.decorrelateJoinPredicate.enabled")
+ .internal()
+ .doc("Decorrelate subqueries with correlated references in join predicates.")
Review Comment:
We should also mention that the decorrelate inner query config
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/DecorrelateInnerQuery.scala:
##########
@@ -804,18 +804,74 @@ object DecorrelateInnerQuery extends PredicateHelper {
(d.copy(child = newChild), joinCond, outerReferenceMap)
case j @ Join(left, right, joinType, condition, _) =>
- val outerReferences = collectOuterReferences(j.expressions)
- // Join condition containing outer references is not supported.
- assert(outerReferences.isEmpty, s"Correlated column is not allowed in join: $j")
- val newOuterReferences = parentOuterReferences ++ outerReferences
- val shouldPushToLeft = joinType match {
+ // Given 'condition', computes the tuple of
+ // (correlated, uncorrelated, equalityCond, predicates, equivalences).
+ // 'correlated' and 'uncorrelated' are the conjuncts with (resp. without)
+ // outer (correlated) references. Furthermore, correlated conjuncts are split
+ // into 'equalityCond' (those that are equalities) and all rest ('predicates').
+ // 'equivalences' track equivalent attributes given 'equalityCond'.
+ def splitCorrelatedPredicate(condition: Option[Expression],
+ isInnerJoin: Boolean,
+ shouldDecorrelatePredicates: Boolean):
Review Comment:
Can we also mention these two parameters in the comment?
##########
sql/core/src/test/resources/sql-tests/inputs/join-lateral.sql:
##########
@@ -101,6 +101,10 @@ SELECT * FROM t1 WHERE c1 = (SELECT MIN(a) FROM t2, LATERAL (SELECT c1 AS a));
-- lateral join inside correlated subquery
SELECT * FROM t1 WHERE c1 = (SELECT MIN(a) FROM t2, LATERAL (SELECT c1 AS a) WHERE c1 = t1.c1);
+-- join condition has a correlated reference to the left side of the lateral join
+SELECT * FROM t1 JOIN lateral (SELECT * FROM t2 JOIN t4 ON t2.c1 = t4.c1 AND t2.c1 = t1.c1);
+SELECT * FROM t1 LEFT JOIN lateral (SELECT * FROM t4 LEFT JOIN t2 ON t2.c1 = t4.c1 AND t2.c1 = t1.c1);
+
Review Comment:
Shall we add one more test for inner join with non-equality join conditions here?
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