allisonwang-db commented on a change in pull request #32303: URL: https://github.com/apache/spark/pull/32303#discussion_r620541594
########## 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), Review comment: Good point. If there is no star in the expanded list using the inner plan, then we don't need to expand it again using the outer plan. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org