mihaibudiu commented on code in PR #4322: URL: https://github.com/apache/calcite/pull/4322#discussion_r2055104439
########## core/src/main/java/org/apache/calcite/rel/rules/MinusToFilterRule.java: ########## @@ -0,0 +1,133 @@ +/* + * 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.Filter; +import org.apache.calcite.rel.core.Minus; +import org.apache.calcite.rex.RexBuilder; +import org.apache.calcite.rex.RexNode; +import org.apache.calcite.rex.RexUtil; +import org.apache.calcite.tools.RelBuilder; +import org.apache.calcite.util.Pair; + +import com.google.common.collect.ImmutableList; + +import org.checkerframework.checker.nullness.qual.Nullable; +import org.immutables.value.Value; + +/** + * Rule that replaces {@link Minus} operator with {@link Filter} + * when both inputs are from the same source with only filter conditions differing. + * + * <p>Example transformation: + * <blockquote><pre> + * SELECT mgr, comm FROM emp WHERE mgr = 12 + * EXCEPT + * SELECT mgr, comm FROM emp WHERE comm = 5 + * + * to + * + * SELECT DISTINCT mgr, comm FROM emp + * WHERE mgr = 12 AND NOT(comm = 5) + * </pre></blockquote> + */ [email protected] +public class MinusToFilterRule + extends RelRule<MinusToFilterRule.Config> + implements TransformationRule { + + /** Creates an MinusToFilterRule. */ + protected MinusToFilterRule(Config config) { + super(config); + } + + //~ Methods ---------------------------------------------------------------- + + @Override public void onMatch(RelOptRuleCall call) { + final Minus minus = call.rel(0); + if (minus.all || minus.getInputs().size() != 2) { + return; + } + final RelBuilder builder = call.builder(); + final RelNode leftInput = call.rel(1); + final Filter rightInput = call.rel(2); + + if (!RexUtil.isDeterministic(rightInput.getCondition())) { + return; + } + + final Pair<RelNode, @Nullable RexNode> leftBase = getUnfilteredInputAndMergeCond(leftInput); + final Pair<RelNode, @Nullable RexNode> rightBase = getUnfilteredInputAndMergeCond(rightInput); + if (!leftBase.left.equals(rightBase.left)) { + return; + } + + // Right input is Filter, right cond should be not null + assert rightBase.right != null; + final RexNode finalCond = leftBase.right != null + ? builder.and(leftBase.right, builder.not(rightBase.right)) + : builder.not(rightBase.right); + + builder.push(leftBase.left) + .filter(finalCond) + .distinct(); + + call.transformTo(builder.build()); + } + + private static Pair<RelNode, @Nullable RexNode> getUnfilteredInputAndMergeCond( + final RelNode node) { + RexBuilder builder = node.getCluster().getRexBuilder(); + RelNode stripped = node.stripped(); + RexNode cond = null; + while (stripped instanceof Filter) { Review Comment: here you handle nested filters; perhaps you should document this in the JavaDoc. ########## core/src/main/java/org/apache/calcite/rel/rules/MinusToFilterRule.java: ########## @@ -0,0 +1,133 @@ +/* + * 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.Filter; +import org.apache.calcite.rel.core.Minus; +import org.apache.calcite.rex.RexBuilder; +import org.apache.calcite.rex.RexNode; +import org.apache.calcite.rex.RexUtil; +import org.apache.calcite.tools.RelBuilder; +import org.apache.calcite.util.Pair; + +import com.google.common.collect.ImmutableList; + +import org.checkerframework.checker.nullness.qual.Nullable; +import org.immutables.value.Value; + +/** + * Rule that replaces {@link Minus} operator with {@link Filter} + * when both inputs are from the same source with only filter conditions differing. + * + * <p>Example transformation: + * <blockquote><pre> + * SELECT mgr, comm FROM emp WHERE mgr = 12 + * EXCEPT + * SELECT mgr, comm FROM emp WHERE comm = 5 + * + * to + * + * SELECT DISTINCT mgr, comm FROM emp + * WHERE mgr = 12 AND NOT(comm = 5) + * </pre></blockquote> + */ [email protected] +public class MinusToFilterRule + extends RelRule<MinusToFilterRule.Config> + implements TransformationRule { + + /** Creates an MinusToFilterRule. */ + protected MinusToFilterRule(Config config) { + super(config); + } + + //~ Methods ---------------------------------------------------------------- + + @Override public void onMatch(RelOptRuleCall call) { + final Minus minus = call.rel(0); + if (minus.all || minus.getInputs().size() != 2) { Review Comment: I expect size cannot be != 2, since the rule would not be applied So this is fine, but it could also be `assert getInputs().size() == 2;` -- This is an automated message from the Apache Git Service. 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