dilipbiswal commented on a change in pull request #26437: [SPARK-29800][SQL]
Plan Exists 's subquery in PlanSubqueries
URL: https://github.com/apache/spark/pull/26437#discussion_r344582313
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File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/subquery.scala
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@@ -106,12 +106,20 @@ object RewritePredicateSubquery extends
Rule[LogicalPlan] with PredicateHelper {
// Filter the plan by applying left semi and left anti joins.
withSubquery.foldLeft(newFilter) {
- case (p, Exists(sub, conditions, _)) =>
- val (joinCond, outerPlan) = rewriteExistentialExpr(conditions, p)
- buildJoin(outerPlan, sub, LeftSemi, joinCond)
- case (p, Not(Exists(sub, conditions, _))) =>
- val (joinCond, outerPlan) = rewriteExistentialExpr(conditions, p)
- buildJoin(outerPlan, sub, LeftAnti, joinCond)
+ case (p, exists @ Exists(sub, conditions, _)) =>
+ if (SubqueryExpression.hasCorrelatedSubquery(exists)) {
+ val (joinCond, outerPlan) = rewriteExistentialExpr(conditions, p)
+ buildJoin(outerPlan, sub, LeftSemi, joinCond)
+ } else {
+ Filter(exists, newFilter)
+ }
+ case (p, Not(exists @ Exists(sub, conditions, _))) =>
+ if (SubqueryExpression.hasCorrelatedSubquery(exists)) {
+ val (joinCond, outerPlan) = rewriteExistentialExpr(conditions, p)
+ buildJoin(outerPlan, sub, LeftAnti, joinCond)
+ } else {
+ Filter(Not(exists), newFilter)
+ }
Review comment:
@AngersZhuuuu I discussed this with Wenchen. Do you think we can safely
inject a "LIMIT 1" into our subplan to expedite its execution ? Pl. lets us
know what you think ?
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