doris/be/src/vec/aggregate_functions/aggregate_function_stddev.cpp

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//   http://www.apache.org/licenses/LICENSE-2.0
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#include "vec/aggregate_functions/aggregate_function_stddev.h"

#include "common/logging.h"
#include "vec/aggregate_functions/aggregate_function_simple_factory.h"
#include "vec/aggregate_functions/factory_helpers.h"
#include "vec/aggregate_functions/helpers.h"
namespace doris::vectorized {

template <template <typename> class AggregateFunctionTemplate, template <typename> class NameData,
          template <typename, typename> class Data, bool is_stddev>
static IAggregateFunction* create_function_single_value(const String& name,
                                                        const DataTypes& argument_types,
                                                        const Array& parameters) {
    auto type = argument_types[0].get();
    if (type->is_nullable()) {
        type = assert_cast<const DataTypeNullable*>(type)->get_nested_type().get();
    }
    WhichDataType which(*type);

#define DISPATCH(TYPE)                                                                         \
    if (which.idx == TypeIndex::TYPE)                                                          \
        return new AggregateFunctionTemplate<NameData<Data<TYPE, BaseData<TYPE, is_stddev>>>>( \
                argument_types);
    FOR_NUMERIC_TYPES(DISPATCH)
#undef DISPATCH
    if (which.is_decimal()) {
        return new AggregateFunctionTemplate<
                NameData<Data<Decimal128, BaseDatadecimal<is_stddev>>>>(argument_types);
    }
    DCHECK(false) << "with unknowed type, failed in  create_aggregate_function_stddev_variance";
    return nullptr;
}

template <bool is_stddev>
AggregateFunctionPtr create_aggregate_function_variance_samp(const std::string& name,
                                                             const DataTypes& argument_types,
                                                             const Array& parameters,
                                                             const bool result_is_nullable) {
    return AggregateFunctionPtr(
            create_function_single_value<AggregateFunctionStddevSamp, VarianceSampData, SampData,
                                         is_stddev>(name, argument_types, parameters));
}

template <bool is_stddev>
AggregateFunctionPtr create_aggregate_function_stddev_samp(const std::string& name,
                                                           const DataTypes& argument_types,
                                                           const Array& parameters,
                                                           const bool result_is_nullable) {
    return AggregateFunctionPtr(
            create_function_single_value<AggregateFunctionStddevSamp, StddevSampData, SampData,
                                         is_stddev>(name, argument_types, parameters));
}

template <bool is_stddev>
AggregateFunctionPtr create_aggregate_function_variance_pop(const std::string& name,
                                                            const DataTypes& argument_types,
                                                            const Array& parameters,
                                                            const bool result_is_nullable) {
    return AggregateFunctionPtr(
            create_function_single_value<AggregateFunctionStddevSamp, VarianceData, PopData,
                                         is_stddev>(name, argument_types, parameters));
}

template <bool is_stddev>
AggregateFunctionPtr create_aggregate_function_stddev_pop(const std::string& name,
                                                          const DataTypes& argument_types,
                                                          const Array& parameters,
                                                          const bool result_is_nullable) {
    return AggregateFunctionPtr(
            create_function_single_value<AggregateFunctionStddevSamp, StddevData, PopData,
                                         is_stddev>(name, argument_types, parameters));
}

void register_aggregate_function_stddev_variance(AggregateFunctionSimpleFactory& factory) {
    factory.register_function("variance_samp", create_aggregate_function_variance_samp<false>);
    factory.register_function("variance", create_aggregate_function_variance_pop<false>);
    factory.register_alias("variance_samp", "var_samp");
    factory.register_alias("variance", "var_pop");
    factory.register_alias("variance", "variance_pop");
    factory.register_function("stddev_samp", create_aggregate_function_stddev_samp<true>);
    factory.register_function("stddev", create_aggregate_function_stddev_pop<true>);
    factory.register_alias("stddev", "stddev_pop");
}
} // namespace doris::vectorized