mihaibudiu commented on code in PR #4280: URL: https://github.com/apache/calcite/pull/4280#discussion_r2033709445
########## core/src/main/java/org/apache/calcite/rel/rules/JoinConditionOrExpansionRule.java: ########## @@ -0,0 +1,299 @@ +/* + * 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.RelOptUtil; +import org.apache.calcite.plan.RelRule; +import org.apache.calcite.rel.RelNode; +import org.apache.calcite.rel.core.Join; +import org.apache.calcite.rel.core.JoinRelType; +import org.apache.calcite.rex.RexNode; +import org.apache.calcite.tools.RelBuilder; + +import org.immutables.value.Value; + +import java.util.ArrayList; +import java.util.List; +import java.util.stream.Collectors; + +/** + * Planner rule that matches a + * {@link org.apache.calcite.rel.core.Join} + * and expands OR clauses in join conditions. + * + * <p>this rule would expand the OR condition into + * two separate join conditions, allowing the optimizer + * to handle these conditions more effectively. + */ [email protected] +public class JoinConditionOrExpansionRule + extends RelRule<JoinConditionOrExpansionRule.Config> + implements TransformationRule { + + /** Creates an JoinConditionExpansionOrRule. */ + protected JoinConditionOrExpansionRule(Config config) { + super(config); + } + + //~ Methods ---------------------------------------------------------------- + + @Override public void onMatch(RelOptRuleCall call) { + Join join = call.rel(0); + RelBuilder relBuilder = call.builder(); + List<RexNode> orConds = RelOptUtil.disjunctions(join.getCondition()); Review Comment: I think you can analyze each of the orConds separately, and make a list of the ones that are "useful". Then you rewrite the OR as (useful0 OR useful1 OR ... OR (everythingelse)), where "everythingelse" is an OR which contains the expressions which are not useful. Then you expand only the useful conditions, and treat "everythingelse" as a simple atomic boolean expression, without regards to its content. Regarding when an expression is "useful": An expression is useful if it is: - a conjunction that has at least one useful subexpression - it is a comparison using EQUALS or IS NOT DISTINCT FROM between two columns in the two inputs of the join There is one more subtlety to worry about: if OR has lazy evaluation, you cannot actually reorder the expressions in the OR, because you may produce runtime exceptions. For example TRUE OR a/0 = b cannot be reordered. -- 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]
