morrySnow commented on code in PR #32188: URL: https://github.com/apache/doris/pull/32188#discussion_r1528446927
########## fe/fe-core/src/main/java/org/apache/doris/nereids/rules/rewrite/ReduceAggregateChildOutputRows.java: ########## @@ -0,0 +1,83 @@ +// 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; + +import org.apache.doris.nereids.exceptions.AnalysisException; +import org.apache.doris.nereids.rules.Rule; +import org.apache.doris.nereids.rules.RuleType; +import org.apache.doris.nereids.trees.expressions.Alias; +import org.apache.doris.nereids.trees.expressions.NamedExpression; +import org.apache.doris.nereids.trees.expressions.functions.agg.AggregateFunction; +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.plans.LimitPhase; +import org.apache.doris.nereids.trees.plans.logical.LogicalAggregate; +import org.apache.doris.nereids.trees.plans.logical.LogicalLimit; +import org.apache.doris.nereids.trees.plans.logical.LogicalProject; + +import java.util.List; +import java.util.Set; +import java.util.stream.Collectors; + +/** ReduceAggregateChildOutputRows + * with group by: + * select max(1) from t1 group by c1; -> select 1 from (select c1 from t1 group by c1); + * without group by: + * select max(1) from t1; -> select max(1) from (select 1 from t1 limit 1) tmp; + * */ +public class ReduceAggregateChildOutputRows extends OneRewriteRuleFactory { + @Override + public Rule build() { + return logicalAggregate().then(agg -> { + Set<AggregateFunction> aggFunctions = agg.getAggregateFunctions(); + // check whether we have aggregate(constant) in all aggregateFunctions + if (!agg.isRewrittenByAggregateConstant() || aggFunctions.isEmpty() || !aggFunctions.stream().allMatch( + f -> (f instanceof Min || f instanceof Max) + && (f.arity() == 1 && f.child(0).isConstant()))) { + return null; + } + + List<NamedExpression> newOutput = agg.getOutputExpressions().stream().map(ne -> { + if (ne instanceof Alias && ne.child(0) instanceof AggregateFunction) { + AggregateFunction f = (AggregateFunction) ne.child(0); + if (f instanceof Min || f instanceof Max) { + return new Alias(ne.getExprId(), f.child(0), ne.getName()); + } else { + throw new AnalysisException("Unexpected aggregate function: " + f); + } + } else { + return ne; + } + }).collect(Collectors.toList()); Review Comment: use ImmutableList Builder to reduce list copy ########## fe/fe-core/src/main/java/org/apache/doris/nereids/rules/rewrite/ReduceAggregateChildOutputRows.java: ########## @@ -0,0 +1,83 @@ +// 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; + +import org.apache.doris.nereids.exceptions.AnalysisException; +import org.apache.doris.nereids.rules.Rule; +import org.apache.doris.nereids.rules.RuleType; +import org.apache.doris.nereids.trees.expressions.Alias; +import org.apache.doris.nereids.trees.expressions.NamedExpression; +import org.apache.doris.nereids.trees.expressions.functions.agg.AggregateFunction; +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.plans.LimitPhase; +import org.apache.doris.nereids.trees.plans.logical.LogicalAggregate; +import org.apache.doris.nereids.trees.plans.logical.LogicalLimit; +import org.apache.doris.nereids.trees.plans.logical.LogicalProject; + +import java.util.List; +import java.util.Set; +import java.util.stream.Collectors; + +/** ReduceAggregateChildOutputRows + * with group by: + * select max(1) from t1 group by c1; -> select 1 from (select c1 from t1 group by c1); + * without group by: + * select max(1) from t1; -> select max(1) from (select 1 from t1 limit 1) tmp; + * */ +public class ReduceAggregateChildOutputRows extends OneRewriteRuleFactory { + @Override + public Rule build() { + return logicalAggregate().then(agg -> { + Set<AggregateFunction> aggFunctions = agg.getAggregateFunctions(); + // check whether we have aggregate(constant) in all aggregateFunctions + if (!agg.isRewrittenByAggregateConstant() || aggFunctions.isEmpty() || !aggFunctions.stream().allMatch( + f -> (f instanceof Min || f instanceof Max) + && (f.arity() == 1 && f.child(0).isConstant()))) { + return null; + } + + List<NamedExpression> newOutput = agg.getOutputExpressions().stream().map(ne -> { Review Comment: avoid to use stream api for better performance -- This is an automated message from the Apache Git Service. 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