peter-toth commented on code in PR #42223: URL: https://github.com/apache/spark/pull/42223#discussion_r1284057348
########## sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/CombineJoinedAggregates.scala: ########## @@ -0,0 +1,132 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.spark.sql.catalyst.optimizer + +import scala.collection.mutable.ArrayBuffer + +import org.apache.spark.sql.catalyst.expressions.{Alias, And, Attribute, AttributeMap, Expression, NamedExpression, Or} +import org.apache.spark.sql.catalyst.expressions.aggregate.AggregateExpression +import org.apache.spark.sql.catalyst.plans.{Cross, FullOuter, Inner, JoinType, LeftOuter, RightOuter} +import org.apache.spark.sql.catalyst.plans.logical.{Aggregate, Filter, Join, LeafNode, LogicalPlan, Project, SerializeFromObject} +import org.apache.spark.sql.catalyst.rules.Rule +import org.apache.spark.sql.catalyst.trees.TreePattern.{AGGREGATE, JOIN} + +/** + * This rule eliminates the [[Join]] if all the join side are [[Aggregate]]s by combine these + * [[Aggregate]]s. This rule also support the nested [[Join]], as long as all the join sides for + * every [[Join]] are [[Aggregate]]s. + * + * Note: this rule doesn't following cases: + * 1. One of the to be merged two [[Aggregate]]s with child [[Filter]] and the other one is not. Review Comment: Merging can always "inflate" data in case of aggregate function columns are different to filter condition columns as those condition columns need to go up to aggregate in the merged query while in the original queries they were pruned after filter. In this case if we alias the conditions to small boolean columns then shuffle data size decrease and less "stressful". The worst case you are referring to is when aggregate function columns are the superset of filter condition columns, but even in this case only small boolean columns are added and the gain is that we don't need to evaluate the filters twice. -- 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. To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org 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
