englefly commented on code in PR #60757: URL: https://github.com/apache/doris/pull/60757#discussion_r3392837049
########## fe/fe-core/src/main/java/org/apache/doris/nereids/rules/rewrite/eageraggregation/PushDownAggregation.java: ########## @@ -0,0 +1,319 @@ +// 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. + +// 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.eageraggregation; + +import org.apache.doris.nereids.jobs.JobContext; +import org.apache.doris.nereids.rules.analysis.NormalizeAggregate; +import org.apache.doris.nereids.rules.rewrite.AdjustNullable; +import org.apache.doris.nereids.trees.expressions.CaseWhen; +import org.apache.doris.nereids.trees.expressions.Expression; +import org.apache.doris.nereids.trees.expressions.NamedExpression; +import org.apache.doris.nereids.trees.expressions.Slot; +import org.apache.doris.nereids.trees.expressions.SlotReference; +import org.apache.doris.nereids.trees.expressions.functions.Function; +import org.apache.doris.nereids.trees.expressions.functions.agg.AggregateFunction; +import org.apache.doris.nereids.trees.expressions.functions.agg.Count; +import org.apache.doris.nereids.trees.expressions.functions.agg.Max; +import org.apache.doris.nereids.trees.expressions.functions.agg.Min; +import org.apache.doris.nereids.trees.expressions.functions.agg.RollUpTrait; +import org.apache.doris.nereids.trees.expressions.functions.agg.Sum; +import org.apache.doris.nereids.trees.expressions.functions.scalar.If; +import org.apache.doris.nereids.trees.expressions.functions.scalar.Nvl; +import org.apache.doris.nereids.trees.expressions.literal.BigIntLiteral; +import org.apache.doris.nereids.trees.expressions.literal.NullLiteral; +import org.apache.doris.nereids.trees.plans.Plan; +import org.apache.doris.nereids.trees.plans.logical.LogicalAggregate; +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.logical.LogicalProject; +import org.apache.doris.nereids.trees.plans.logical.LogicalRelation; +import org.apache.doris.nereids.trees.plans.logical.LogicalUnion; +import org.apache.doris.nereids.trees.plans.visitor.CustomRewriter; +import org.apache.doris.nereids.trees.plans.visitor.DefaultPlanRewriter; +import org.apache.doris.nereids.util.ExpressionUtils; +import org.apache.doris.qe.SessionVariable; + +import com.google.common.collect.Lists; +import com.google.common.collect.Maps; +import com.google.common.collect.Sets; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.ArrayList; +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import java.util.Optional; +import java.util.Set; +import java.util.stream.Collectors; + +/** + * push down aggregation + */ +public class PushDownAggregation extends DefaultPlanRewriter<JobContext> implements CustomRewriter { + private static final Logger LOG = LoggerFactory.getLogger(PushDownAggregation.class); + + public final EagerAggRewriter writer = new EagerAggRewriter(); + + private final Set<Class> pushDownAggFunctionSet = Sets.newHashSet( + Count.class, + Sum.class, + Max.class, + Min.class); + + private final Set<Class> acceptNodeType = Sets.newHashSet( + LogicalUnion.class, + LogicalProject.class, + LogicalFilter.class, + LogicalRelation.class, + LogicalJoin.class); + + @Override + public Plan rewriteRoot(Plan plan, JobContext jobContext) { + if (SessionVariable.isFeDebug()) { + try { + new AdjustNullable(false).rewriteRoot(plan, null); + } catch (Exception e) { + LOG.warn("(PushDownAggregation) input plan has nullable problem", e); + return plan; + } + } + int mode = SessionVariable.getEagerAggregationMode(); + if (mode < 0) { + return plan; + } else { + Plan result = plan.accept(this, jobContext); + if (SessionVariable.isFeDebug()) { + result = new AdjustNullable(true).rewriteRoot(result, null); + } + return result; + } + } + + @Override + public Plan visitLogicalAggregate(LogicalAggregate<? extends Plan> agg, JobContext context) { + Plan newChild = agg.child().accept(this, context); + if (newChild != agg.child()) { + return agg.withChildren(newChild); + } + + if (agg.getSourceRepeat().isPresent()) { + return agg; + } + + List<SlotReference> groupKeys = new ArrayList<>(); + for (Expression groupKey : agg.getGroupByExpressions()) { + if (groupKey instanceof SlotReference) { + groupKeys.add((SlotReference) groupKey); + } else { + SessionVariable.throwAnalysisExceptionWhenFeDebug( + "PushDownAggregation failed: agg is not normalized\n " + + agg.treeString()); + return agg; + } + } + + Set<AggregateFunction> aggFunctions = Sets.newHashSet(); + boolean hasDecomposedAggIf = false; + boolean hasCaseWhen = false; + Map<NamedExpression, List<AggregateFunction>> aggFunctionsForOutputExpressions = Maps.newHashMap(); + for (NamedExpression aggOutput : agg.getOutputExpressions()) { + List<AggregateFunction> funcs = Lists.newArrayList(); + aggFunctionsForOutputExpressions.put(aggOutput, funcs); + for (Object obj : aggOutput.collect(AggregateFunction.class::isInstance)) { + AggregateFunction aggFunction = (AggregateFunction) obj; + if (aggFunction.isDistinct()) { + return agg; + } + if (pushDownAggFunctionSet.contains(aggFunction.getClass())) { + // CaseWhen and If (which CASE WHEN is normalized into) must both be checked. + // When an agg function contains an If/CaseWhen whose condition tests IS NULL + // (e.g. count(if(col IS NULL, value, NULL))), pushing it to the nullable side + // of an outer join produces wrong results: null-extended rows make "col IS NULL" + // TRUE at the top level, but the pre-aggregated count slot becomes NULL after + // null-extension, and ifnull(sum(NULL), 0) = 0 instead of the correct 1. + if (!hasCaseWhen && aggFunction.anyMatch(e -> e instanceof CaseWhen || e instanceof If)) { + hasCaseWhen = true; + } Review Comment: 不会有问题. ifnull(x, y) 会作为一个整体下推. if(a>0, b, c) 拆开推的原因是 a 可以来自左表, b/c 可以来自右表,所以拆开后可以推的范围更大. ifnull(x, y) 相当于 if(x is null, x, y), 如果条件和 value 来自同一张表,那么也就没有拆开的必要了,只能当做整体下推. 类似的函数也都整体下推 IF(cond, a, b) | 条件为真返回 a，否则返回 b IFNULL(a, b) | a 不为 NULL 返回 a，否则返回 b（别名：NVL） CASE WHEN | 多分支条件逻辑，类似 switch-case COALESCE(a, b, ...) | 返回参数列表中第一个非 NULL 的值 NULLIF(a, b) | 若 a = b 返回 NULL，否则返回 a LEAST(a, b, ...) | 返回多个参数中的最小值，任一为 NULL 则返回 NULL GREATEST(a, b, ...) | 返回多个参数中的最大值，任一为 NULL 则返回 NULL NULL_OR_EMPTY(str) | 字符串为 NULL 或空串时返回 true NOT_NULL_OR_EMPTY(str) | 字符串既不为 NULL 也不为空串时返回 true -- This is an automated message from the Apache Git Service. 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