maropu commented on a change in pull request #23750: [SPARK-19712][SQL] Pushing
Left Semi and Left Anti joins through Project, Aggregate, Window, Union etc.
URL: https://github.com/apache/spark/pull/23750#discussion_r256829220
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
##########
@@ -1188,6 +1189,190 @@ object PushDownPredicate extends Rule[LogicalPlan]
with PredicateHelper {
}
}
+object PushDownLeftSemiAntiJoin extends Rule[LogicalPlan] with PredicateHelper
{
+ def apply(plan: LogicalPlan): LogicalPlan = plan transform {
+ // Similar to the above Filter over Project
+ // LeftSemi/LeftAnti over Project
+ case join @ Join(p @ Project(pList, gChild), rightOp,
LeftSemiOrAnti(joinType), joinCond, hint)
+ if pList.forall(_.deterministic) &&
!ScalarSubquery.hasScalarSubquery(pList) &&
+ canPushThroughCondition(Seq(gChild), joinCond, rightOp) =>
+ if (joinCond.isEmpty) {
+ // No join condition, just push down the Join below Project
+ Project(pList, Join(gChild, rightOp, joinType, joinCond, hint))
+ } else {
+ // Create a map of Aliases to their values from the child projection.
+ // e.g., 'SELECT a + b AS c, d ...' produces Map(c -> a + b).
+ val aliasMap = AttributeMap(pList.collect {
+ case a: Alias => (a.toAttribute, a.child)
+ })
+ val newJoinCond = if (aliasMap.nonEmpty) {
+ Option(replaceAlias(joinCond.get, aliasMap))
+ } else {
+ joinCond
+ }
+ Project(pList, Join(gChild, rightOp, joinType, newJoinCond, hint))
+ }
+
+ // Similar to the above Filter over Aggregate
+ // LeftSemi/LeftAnti over Aggregate
+ case join @ Join(aggregate: Aggregate, rightOp, LeftSemiOrAnti(joinType),
joinCond, hint)
+ if aggregate.aggregateExpressions.forall(_.deterministic)
+ && aggregate.groupingExpressions.nonEmpty =>
+ if (joinCond.isEmpty) {
+ // No join condition, just push down Join below Aggregate
+ aggregate.copy(child = Join(aggregate.child, rightOp, joinType,
joinCond, hint))
+ } else {
+ // Find all the aliased expressions in the aggregate list that don't
include any actual
+ // AggregateExpression, and create a map from the alias to the
expression
+ val aliasMap = AttributeMap(aggregate.aggregateExpressions.collect {
Review comment:
Can we share the code and comment with `PushDownPredicate`?
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