NobiGo commented on code in PR #4244: URL: https://github.com/apache/calcite/pull/4244#discussion_r2020315955
########## core/src/main/java/org/apache/calcite/rel/rules/IntersectReorderRule.java: ########## @@ -0,0 +1,98 @@ +/* + * 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.calcite.rel.rules; + +import org.apache.calcite.plan.RelOptRuleCall; +import org.apache.calcite.plan.RelRule; +import org.apache.calcite.rel.RelNode; +import org.apache.calcite.rel.core.Intersect; +import org.apache.calcite.rel.logical.LogicalIntersect; +import org.apache.calcite.rel.metadata.RelMetadataQuery; +import org.apache.calcite.tools.RelBuilder; +import org.apache.calcite.util.Pair; + +import org.immutables.value.Value; + +import java.util.ArrayList; +import java.util.List; +import java.util.stream.Collectors; + +/** + * Planner rule that reorders inputs of an {@link Intersect} to put smaller inputs first. + * This helps reduce the size of intermediate results. + * + * <p>Intersect(A, B, ...) where B is smallest will reorder to Intersect(B, A, ...) + */ [email protected] +public class IntersectReorderRule extends RelRule<IntersectReorderRule.Config> { + /** Creates an IntersectReorderRule. */ + protected IntersectReorderRule(Config config) { + super(config); + } + + @Override public void onMatch(RelOptRuleCall call) { + final Intersect intersect = call.rel(0); + final RelMetadataQuery mq = call.getMetadataQuery(); + final List<RelNode> inputs = intersect.getInputs(); + + final List<Pair<RelNode, Double>> inputsWithRowCounts = new ArrayList<>(); + + for (RelNode input : inputs) { + Double rowCount = mq.getRowCount(input); Review Comment: In fact, the Cumulative Cost currently being compared is also RowCount. The Cumulative Cost currently consists of three parts: RowCount、CPU and IO. I don't understand why the data volume returned is large despite being a low-cost solution. This actually depends on the implementation of CBO. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
