allisonwang-db commented on a change in pull request #32303:
URL: https://github.com/apache/spark/pull/32303#discussion_r620556049
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
##########
@@ -2234,6 +2270,74 @@ class Analyzer(override val catalogManager:
CatalogManager)
}
}
+ /**
+ * This rule resolves lateral joins.
+ */
+ object ResolveLateralJoin extends Rule[LogicalPlan] {
+ import ResolveReferences._
+
+ /**
+ * Build a project list for Project/Aggregate and expand the star if
possible by first using
+ * the inner query plan. If failed, use the outer query plan to expand the
star and wrap all
+ * expanded attributes in [[OuterReference]]s.
+ */
+ private def expandOuterReference(
+ expressions: Seq[NamedExpression],
+ inner: LogicalPlan,
+ outer: LogicalPlan): Seq[NamedExpression] = {
+
+ def expandInner(star: Star): Seq[NamedExpression] =
+ star.expand(inner, resolver)
+
+ // Leave the star unchanged if the outer plan is unable to resolve the
star.
+ // Otherwise wrap the resolved attributes in outer references.
+ def expandOuter(star: Star): Seq[NamedExpression] = {
+ star.expand(outer, resolver).map {
+ case s: Star => s
+ case other => other
+ .transform { case a: Attribute => OuterReference(a) }
+ .asInstanceOf[NamedExpression]
+ }
+ }
+
+ buildExpandedProjectList(
+ buildExpandedProjectList(expressions, inner, expandInner),
+ outer,
+ expandOuter)
+ }
+
+ /**
+ * Resolve the right sub-tree by first using the right query plan itself,
and then try
+ * resolving the unresolved attributes and star expressions using the left
query plan.
+ */
+ private def resolveRightChild(right: LogicalPlan, left: LogicalPlan):
LogicalPlan = {
+ right.resolveOperators {
+ case p: LogicalPlan if !p.childrenResolved => p
+ case p: Project if containsStar(p.projectList) =>
+ p.copy(projectList = expandOuterReference(p.projectList, p.child,
left))
+ case a: Aggregate if containsStar(a.aggregateExpressions) =>
+ a.copy(aggregateExpressions =
+ expandOuterReference(a.aggregateExpressions, a.child, left))
+ case p: LogicalPlan if !p.resolved =>
+ p transformExpressions {
+ case u @ UnresolvedAttribute(nameParts) =>
+ withPosition(u) {
+ p.resolveChildren(nameParts, resolver)
+ .orElse(resolveLiteralFunction(nameParts))
+ .orElse(resolveOuterReference(nameParts, left))
Review comment:
Hmm I am getting this optimized plan from the query:
```
scala> sql("SELECT * FROM t1, LATERAL (SELECT c2 FROM t2 WHERE t1.c1 =
t2.c1) tx(a);").explain(true)
...
== Optimized Logical Plan ==
Project [c1#0, c2#1, a#8]
+- Join Inner, (c1#0 = c1#4)
:- LocalRelation [c1#0, c2#1]
+- LocalRelation [a#8, c1#4]
```
The outer references inside the Filter should have been pulled up as join
conditions.
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