xiedeyantu commented on code in PR #4397: URL: https://github.com/apache/calcite/pull/4397#discussion_r2103708225
########## core/src/main/java/org/apache/calcite/rel/rules/BottomDecorrelateRule.java: ########## @@ -0,0 +1,109 @@ +/* + * 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.Correlate; +import org.apache.calcite.sql2rel.RelDecorrelator; + +import org.immutables.value.Value; + +import java.util.ArrayList; +import java.util.List; + +/** + * This rule invokes the standard decorrelator {@link RelDecorrelator} on subplans of a query + * plan that are rooted at a {@link Correlate} node. By invoking this rule repeatedly + * one essentially obtains a bottom-up application of the decorrelator, where + * {@link Correlate} nodes closer to leaves are processed first. This strategy may + * enable decorrelating plans where applying the decorrelator at the root may fail. + * (The standard decorrelator is all-or-nothing, if it fails, it returns the original plan + * unchanged. This strategy may still simplify some plans by decorrelating parts of them). + */ [email protected] +public class BottomDecorrelateRule Review Comment: Would it be better to change the rule name to `BottomUpDecorrelateRule`? ########## core/src/main/java/org/apache/calcite/rel/rules/BottomDecorrelateRule.java: ########## @@ -0,0 +1,109 @@ +/* + * 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.Correlate; +import org.apache.calcite.sql2rel.RelDecorrelator; + +import org.immutables.value.Value; + +import java.util.ArrayList; +import java.util.List; + +/** + * This rule invokes the standard decorrelator {@link RelDecorrelator} on subplans of a query + * plan that are rooted at a {@link Correlate} node. By invoking this rule repeatedly + * one essentially obtains a bottom-up application of the decorrelator, where + * {@link Correlate} nodes closer to leaves are processed first. This strategy may + * enable decorrelating plans where applying the decorrelator at the root may fail. + * (The standard decorrelator is all-or-nothing, if it fails, it returns the original plan + * unchanged. This strategy may still simplify some plans by decorrelating parts of them). + */ [email protected] +public class BottomDecorrelateRule + extends RelRule<BottomDecorrelateRule.Config> + implements TransformationRule { + + protected BottomDecorrelateRule(Config config) { + super(config); + } + + //~ Methods ---------------------------------------------------------------- + + @Override public void onMatch(RelOptRuleCall call) { + Correlate cor = call.rel(0); + for (RelNode input : cor.stripped().getInputs()) { + if (containsCorrelate(input)) { + // Give up + return; + } + } + + RelNode stripped = stripRecursively(cor); + RelNode rel = RelDecorrelator.decorrelateQuery(stripped, call.builder()); + if (rel != stripped + && !containsCorrelate(rel) Review Comment: There is a small problem here. If the logic of the standard decorrelator is all-or-nothing, then is it enough to compare the value `rel != stripped`? -- This is an automated message from the Apache Git Service. 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