be/src/exprs/aggregate/aggregate_function_avg.cpp

// 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.
// This file is copied from
// https://github.com/ClickHouse/ClickHouse/blob/master/src/AggregateFunctions/AggregateFunctionAvg.cpp
// and modified by Doris

#include "exprs/aggregate/aggregate_function_avg.h"

#include "core/data_type/define_primitive_type.h"
#include "core/field.h"
#include "exprs/aggregate/aggregate_function_simple_factory.h"
#include "exprs/aggregate/helpers.h"

namespace doris {
#include "common/compile_check_begin.h"

constexpr PrimitiveType result_type(PrimitiveType T) {
    if (T == TYPE_LARGEINT || T == TYPE_BIGINT) {
        return TYPE_LARGEINT;
    } else if (is_int_or_bool(T)) {
        return TYPE_BIGINT;
    } else if (is_float_or_double(T) || is_time_type(T)) {
        return TYPE_DOUBLE;
    } else if (is_decimalv3(T) && T != TYPE_DECIMAL256) {
        return TYPE_DECIMAL128I;
    } else {
        return T;
    }
}

// TODO: use result type got from FE plan
template <PrimitiveType T>
struct Avg {
    static constexpr PrimitiveType ResultPType = T == TYPE_DECIMALV2 ? T : TYPE_DOUBLE;
    using Function = AggregateFunctionAvg<T, ResultPType, AggregateFunctionAvgData<result_type(T)>>;
};

template <PrimitiveType T>
using AggregateFuncAvg = typename Avg<T>::Function;

// use result type got from FE plan
template <PrimitiveType InputType, PrimitiveType ResultType>
struct AvgDecimalV3 {
    using Function =
            AggregateFunctionAvg<InputType, ResultType, AggregateFunctionAvgData<ResultType>>;
};

template <PrimitiveType InputType, PrimitiveType ResultType>
using AggregateFuncAvgDecimalV3 = typename AvgDecimalV3<InputType, ResultType>::Function;

void register_aggregate_function_avg(AggregateFunctionSimpleFactory& factory) {
    AggregateFunctionCreator creator = [&](const std::string& name, const DataTypes& types,
                                           const DataTypePtr& result_type,
                                           const bool result_is_nullable,
                                           const AggregateFunctionAttr& attr) {
        if (is_decimalv3(types[0]->get_primitive_type())) {
            return creator_with_type_list<TYPE_DECIMAL32, TYPE_DECIMAL64, TYPE_DECIMAL128I,
                                          TYPE_DECIMAL256>::
                    creator_with_result_type<AggregateFuncAvgDecimalV3>(name, types, result_type,
                                                                        result_is_nullable, attr);
        } else {
            return creator_with_type_list<
                    TYPE_TINYINT, TYPE_SMALLINT, TYPE_INT, TYPE_BIGINT, TYPE_LARGEINT, TYPE_DOUBLE,
                    TYPE_DECIMALV2>::creator<AggregateFuncAvg>(name, types, result_type,
                                                               result_is_nullable, attr);
        }
    };
    factory.register_function_both("avg", creator);
}
} // namespace doris