gortiz commented on code in PR #14495: URL: https://github.com/apache/pinot/pull/14495#discussion_r1850241625
########## pinot-query-planner/src/main/java/org/apache/pinot/query/planner/logical/EquivalentStagesReplacer.java: ########## @@ -0,0 +1,79 @@ +/** + * 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.pinot.query.planner.logical; + +import org.apache.pinot.query.planner.plannode.MailboxReceiveNode; +import org.apache.pinot.query.planner.plannode.MailboxSendNode; +import org.apache.pinot.query.planner.plannode.PlanNode; +import org.apache.pinot.query.planner.plannode.PlanNodeVisitor; + + +/** + * EquivalentStageReplacer is used to replace equivalent stages in the query plan. + * + * Given a {@link org.apache.pinot.query.planner.plannode.PlanNode} and a + * {@link GroupedStages}, modifies the plan node to replace equivalent stages. + * + * For each {@link MailboxReceiveNode} in the plan, if the sender is not the leader of the group, + * replaces the sender with the leader. + * The leader is also updated to include the receiver in its list of receivers. + */ +public class EquivalentStagesReplacer { + private EquivalentStagesReplacer() { + } + + /** + * Replaces the equivalent stages in the query plan. + * + * @param root Root plan node + * @param equivalentStages Equivalent stages + */ + public static void replaceEquivalentStages(PlanNode root, GroupedStages equivalentStages) { + root.visit(Replacer.INSTANCE, equivalentStages); + } + + private static class Replacer extends PlanNodeVisitor.DepthFirstVisitor<Void, GroupedStages> { + private static final Replacer INSTANCE = new Replacer(); + + private Replacer() { + } + + @Override + public Void visitMailboxReceive(MailboxReceiveNode node, GroupedStages equivalenceGroups) { + MailboxSendNode sender = node.getSender(); + MailboxSendNode leader = equivalenceGroups.getGroup(sender).first(); + if (canSubstitute(sender, leader)) { + // we don't want to visit the children of the node given it is going to be pruned + node.setSender(leader); + leader.addReceiver(node); + } else { + visitMailboxSend(leader, equivalenceGroups); + } + return null; + } + + private boolean canSubstitute(MailboxSendNode actualSender, MailboxSendNode leader) { + return actualSender != leader // we don't need to replace the leader with itself + // the leader is already sending to this stage. Given we don't have the ability to send to multiple + // receivers in the same stage, we cannot optimize this case right now. + // If this case seems to be useful, it can be supported in the future. + && !leader.getReceiverStages().intersects(actualSender.getReceiverStages()); + } Review Comment: Yes, but also recursive cases like: - join <-- it also applies here - left: join - left: read T1 - right: read T2 - right: join - left: read T1 - right: read T2 -- 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: commits-unsubscr...@pinot.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@pinot.apache.org For additional commands, e-mail: commits-h...@pinot.apache.org
