wangshuo128 commented on code in PR #10890: URL: https://github.com/apache/doris/pull/10890#discussion_r923093349
########## fe/fe-core/src/main/java/org/apache/doris/nereids/rules/rewrite/logical/ReorderJoin.java: ########## @@ -0,0 +1,201 @@ +// 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.doris.nereids.rules.rewrite.logical; + +import org.apache.doris.nereids.rules.Rule; +import org.apache.doris.nereids.rules.RuleType; +import org.apache.doris.nereids.rules.rewrite.OneRewriteRuleFactory; +import org.apache.doris.nereids.trees.expressions.EqualTo; +import org.apache.doris.nereids.trees.expressions.Expression; +import org.apache.doris.nereids.trees.expressions.Slot; +import org.apache.doris.nereids.trees.expressions.visitor.SlotExtractor; +import org.apache.doris.nereids.trees.plans.JoinType; +import org.apache.doris.nereids.trees.plans.Plan; +import org.apache.doris.nereids.trees.plans.logical.LogicalFilter; +import org.apache.doris.nereids.trees.plans.logical.LogicalJoin; +import org.apache.doris.nereids.trees.plans.visitor.PlanVisitor; +import org.apache.doris.nereids.util.ExpressionUtils; + +import java.util.ArrayList; +import java.util.HashSet; +import java.util.List; +import java.util.Map; +import java.util.Optional; +import java.util.Set; +import java.util.stream.Collectors; + +/** + * Try to eliminate cross join via finding join conditions in filters and change the join orders. + * <p> + * <pre> + * For example: + * + * input: + * SELECT * FROM t1, t2, t3 WHERE t1.id=t3.id AND t2.id=t3.id + * + * output: + * SELECT * FROM t1 JOIN t3 ON t1.id=t3.id JOIN t2 ON t2.id=t3.id + * </pre> + * </p> + * TODO: This is tested by SSB queries currently, add more `unit` test for this rule + * when we have a plan building and comparing framework. + */ +public class ReorderJoin extends OneRewriteRuleFactory { + @Override + public Rule<Plan> build() { + return logicalFilter(subTree(LogicalJoin.class, LogicalFilter.class)).then(filter -> { + PlanCollector collector = new PlanCollector(); + filter.accept(collector, null); + List<Plan> joinInputs = collector.joinInputs; + List<Expression> conjuncts = collector.conjuncts; + + if (joinInputs.size() >= 3 && !conjuncts.isEmpty()) { + return reorderJoins(joinInputs, conjuncts); + } else { + return filter; + } + }).toRule(RuleType.REORDER_JOIN); + } + + private Plan reorderJoins(List<Plan> joinInputs, List<Expression> conjuncts) { + if (joinInputs.size() == 2) { + Set<Slot> joinOutput = getJoinOutput(joinInputs.get(0), joinInputs.get(1)); + Map<Boolean, List<Expression>> split = splitConjuncts(conjuncts, joinOutput); + List<Expression> joinConditions = split.get(true); + List<Expression> nonJoinConditions = split.get(false); + + Optional<Expression> cond; + if (joinConditions.isEmpty()) { + cond = Optional.empty(); + } else { + cond = Optional.of(ExpressionUtils.and(joinConditions)); + } + + LogicalJoin join = new LogicalJoin(JoinType.INNER_JOIN, cond, joinInputs.get(0), joinInputs.get(1)); + if (nonJoinConditions.isEmpty()) { + return join; + } else { + return new LogicalFilter(ExpressionUtils.and(nonJoinConditions), join); + } + } else { + Plan left = joinInputs.get(0); + List<Plan> candidate = joinInputs.subList(1, joinInputs.size()); + + List<Slot> leftOutput = left.getOutput(); + Optional<Plan> rightOpt = candidate.stream().filter(right -> { + List<Slot> rightOutput = right.getOutput(); + + Set<Slot> joinOutput = getJoinOutput(left, right); + Optional<Expression> joinCond = conjuncts.stream() + .filter(expr -> { + Set<Slot> exprInputSlots = SlotExtractor.extractSlot(expr); + if (exprInputSlots.isEmpty()) { + return false; + } + + if (new HashSet<>(leftOutput).containsAll(exprInputSlots)) { + return false; + } + + if (new HashSet<>(rightOutput).containsAll(exprInputSlots)) { + return false; + } + + return joinOutput.containsAll(exprInputSlots); + }).findFirst(); + return joinCond.isPresent(); + }).findFirst(); + + Plan right = rightOpt.orElseGet(() -> candidate.get(1)); + Set<Slot> joinOutput = getJoinOutput(left, right); + Map<Boolean, List<Expression>> split = splitConjuncts(conjuncts, joinOutput); + List<Expression> joinConditions = split.get(true); + List<Expression> nonJoinConditions = split.get(false); + + Optional<Expression> cond; + if (joinConditions.isEmpty()) { + cond = Optional.empty(); + } else { + cond = Optional.of(ExpressionUtils.and(joinConditions)); + } + + LogicalJoin join = new LogicalJoin(JoinType.INNER_JOIN, cond, left, right); + + List<Plan> newInputs = new ArrayList<>(); + newInputs.add(join); + newInputs.addAll(candidate.stream().filter(plan -> !right.equals(plan)).collect(Collectors.toList())); + return reorderJoins(newInputs, nonJoinConditions); + } + } + + private Set<Slot> getJoinOutput(Plan left, Plan right) { + HashSet<Slot> joinOutput = new HashSet<>(); + joinOutput.addAll(left.getOutput()); + joinOutput.addAll(right.getOutput()); + return joinOutput; + } + + private Map<Boolean, List<Expression>> splitConjuncts(List<Expression> conjuncts, Set<Slot> slots) { + return conjuncts.stream().collect(Collectors.partitioningBy( + // TODO: support non equal to conditions. + expr -> expr instanceof EqualTo && slots.containsAll(SlotExtractor.extractSlot(expr)))); Review Comment: Actually, this doesn't make a big difference. This rule push predicates with slots from one input into the join. `PushPredicateThroughJoin` could push this kind of predicates through join, both in join conditions or filter predicates. -- 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...@doris.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@doris.apache.org For additional commands, e-mail: commits-h...@doris.apache.org
