HappenLee commented on code in PR #66942: URL: https://github.com/apache/doris/pull/66942#discussion_r3849334414
########## fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/combinator/CombineCombinator.java: ########## @@ -0,0 +1,164 @@ +// 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.trees.expressions.functions.combinator; + +import org.apache.doris.catalog.BuiltinAggregateFunctions; +import org.apache.doris.catalog.Env; +import org.apache.doris.catalog.FunctionRegistry; +import org.apache.doris.catalog.FunctionSignature; +import org.apache.doris.common.Pair; +import org.apache.doris.nereids.exceptions.AnalysisException; +import org.apache.doris.nereids.trees.expressions.Expression; +import org.apache.doris.nereids.trees.expressions.OrderExpression; +import org.apache.doris.nereids.trees.expressions.functions.AggCombinerFunctionBuilder; +import org.apache.doris.nereids.trees.expressions.functions.AlwaysNotNullable; +import org.apache.doris.nereids.trees.expressions.functions.BoundFunction; +import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature; +import org.apache.doris.nereids.trees.expressions.functions.ExpressionTrait; +import org.apache.doris.nereids.trees.expressions.functions.Function; +import org.apache.doris.nereids.trees.expressions.functions.FunctionBuilder; +import org.apache.doris.nereids.trees.expressions.functions.agg.AggregateFunction; +import org.apache.doris.nereids.trees.expressions.functions.agg.AggregateFunctionParams; +import org.apache.doris.nereids.trees.expressions.functions.agg.AggregatePhase; +import org.apache.doris.nereids.trees.expressions.functions.agg.RollUpTrait; +import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor; +import org.apache.doris.nereids.types.AggStateType; +import org.apache.doris.nereids.types.DataType; + +import com.google.common.collect.ImmutableList; + +import java.util.List; +import java.util.Objects; + +/** + * Aggregate inputs into the nested function's serialized state. + */ +public class CombineCombinator extends AggregateFunction + implements ExplicitlyCastableSignature, AlwaysNotNullable, Combinator, RollUpTrait { + + private final AggregateFunction nested; + private final AggStateType returnType; + + /** Constructor of CombineCombinator. */ + public CombineCombinator(List<Expression> arguments, AggregateFunction nested) { + super(nested.getName() + AggCombinerFunctionBuilder.COMBINE_SUFFIX, arguments); + checkArguments(arguments, nested); + this.nested = Objects.requireNonNull(nested, "nested can not be null"); + this.returnType = createReturnType(arguments, nested); + } + + private CombineCombinator(AggregateFunctionParams functionParams, AggregateFunction nested) { + super(functionParams); + checkArguments(functionParams.arguments, nested); + this.nested = Objects.requireNonNull(nested, "nested can not be null"); + this.returnType = createReturnType(functionParams.arguments, nested); + } + + private static void checkArguments(List<Expression> arguments, AggregateFunction nested) { + if (arguments.isEmpty()) { + throw new AnalysisException(String.format( + "%s_combine requires at least one argument", nested.getName())); + } + for (Expression argument : arguments) { + if (argument instanceof OrderExpression) { + throw new AnalysisException(String.format( + "%s_combine doesn't support order by expression", nested.getName())); + } + } + } + + private static AggStateType createReturnType(List<Expression> arguments, AggregateFunction nested) { + return new AggStateType(nested.getName(), + arguments.stream().map(ExpressionTrait::getDataType) + .collect(ImmutableList.toImmutableList()), + arguments.stream().map(ExpressionTrait::nullable) + .collect(ImmutableList.toImmutableList()), + BuiltinAggregateFunctions.INSTANCE.aggFuncNameNullableMap.get(nested.getName())); + } + + @Override + public CombineCombinator withChildren(List<Expression> children) { Review Comment: Thanks for pointing this out. For this PR, `_combine` is intentionally required to produce an AggState whose type exactly matches the target AggState, including the nested function, argument subtypes, and argument nullability. Retargeting or coercing a `_combine` producer across an aggregate boundary is not part of the supported contract. Explicit CAST or INSERT sink coercion between non-identical AggState types should therefore be rejected; callers need to cast or otherwise adjust the raw inputs before `_combine` so that it produces the exact target type. We will not add producer-aware AggState coercion for `_combine` in this PR. -- 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. 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