ClickHouse/src/AggregateFunctions/AggregateFunctionGroupArray.cpp

#include <AggregateFunctions/AggregateFunctionFactory.h>
#include <AggregateFunctions/AggregateFunctionGroupArray.h>
#include <AggregateFunctions/Helpers.h>
#include <AggregateFunctions/FactoryHelpers.h>
#include <DataTypes/DataTypeDate.h>
#include <DataTypes/DataTypeDateTime.h>


namespace DB
{
struct Settings;

namespace ErrorCodes
{
    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
    extern const int BAD_ARGUMENTS;
}

namespace
{

template <template <typename, typename> class AggregateFunctionTemplate, typename Data, typename ... TArgs>
IAggregateFunction * createWithNumericOrTimeType(const IDataType & argument_type, TArgs && ... args)
{
    WhichDataType which(argument_type);
    if (which.idx == TypeIndex::Date) return new AggregateFunctionTemplate<UInt16, Data>(std::forward<TArgs>(args)...);
    if (which.idx == TypeIndex::DateTime) return new AggregateFunctionTemplate<UInt32, Data>(std::forward<TArgs>(args)...);
    return createWithNumericType<AggregateFunctionTemplate, Data, TArgs...>(argument_type, std::forward<TArgs>(args)...);
}


template <typename Trait, typename ... TArgs>
inline AggregateFunctionPtr createAggregateFunctionGroupArrayImpl(const DataTypePtr & argument_type, const Array & parameters, TArgs ... args)
{
    if (auto res = createWithNumericOrTimeType<GroupArrayNumericImpl, Trait>(*argument_type, argument_type, parameters, std::forward<TArgs>(args)...))
        return AggregateFunctionPtr(res);

    WhichDataType which(argument_type);
    if (which.idx == TypeIndex::String)
        return std::make_shared<GroupArrayGeneralImpl<GroupArrayNodeString, Trait>>(argument_type, parameters, std::forward<TArgs>(args)...);

    return std::make_shared<GroupArrayGeneralImpl<GroupArrayNodeGeneral, Trait>>(argument_type, parameters, std::forward<TArgs>(args)...);

    // Link list implementation doesn't show noticeable performance improvement
    // if (which.idx == TypeIndex::String)
    //     return std::make_shared<GroupArrayGeneralListImpl<GroupArrayListNodeString, Trait>>(argument_type, std::forward<TArgs>(args)...);

    // return std::make_shared<GroupArrayGeneralListImpl<GroupArrayListNodeGeneral, Trait>>(argument_type, std::forward<TArgs>(args)...);
}


AggregateFunctionPtr createAggregateFunctionGroupArray(
    const std::string & name, const DataTypes & argument_types, const Array & parameters, const Settings *)
{
    assertUnary(name, argument_types);

    bool limit_size = false;
    UInt64 max_elems = std::numeric_limits<UInt64>::max();

    if (parameters.empty())
    {
        // no limit
    }
    else if (parameters.size() == 1)
    {
        auto type = parameters[0].getType();
        if (type != Field::Types::Int64 && type != Field::Types::UInt64)
               throw Exception("Parameter for aggregate function " + name + " should be positive number", ErrorCodes::BAD_ARGUMENTS);

        if ((type == Field::Types::Int64 && parameters[0].get<Int64>() < 0) ||
            (type == Field::Types::UInt64 && parameters[0].get<UInt64>() == 0))
            throw Exception("Parameter for aggregate function " + name + " should be positive number", ErrorCodes::BAD_ARGUMENTS);

        limit_size = true;
        max_elems = parameters[0].get<UInt64>();
    }
    else
        throw Exception("Incorrect number of parameters for aggregate function " + name + ", should be 0 or 1",
            ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

    if (!limit_size)
        return createAggregateFunctionGroupArrayImpl<GroupArrayTrait<false, Sampler::NONE>>(argument_types[0], parameters);
    else
        return createAggregateFunctionGroupArrayImpl<GroupArrayTrait<true, Sampler::NONE>>(argument_types[0], parameters, max_elems);
}

AggregateFunctionPtr createAggregateFunctionGroupArraySample(
    const std::string & name, const DataTypes & argument_types, const Array & parameters, const Settings *)
{
    assertUnary(name, argument_types);

    if (parameters.size() != 1 && parameters.size() != 2)
        throw Exception("Incorrect number of parameters for aggregate function " + name + ", should be 1 or 2",
            ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

    auto get_parameter = [&](size_t i)
    {
        auto type = parameters[i].getType();
        if (type != Field::Types::Int64 && type != Field::Types::UInt64)
            throw Exception("Parameter for aggregate function " + name + " should be positive number", ErrorCodes::BAD_ARGUMENTS);

        if ((type == Field::Types::Int64 && parameters[i].get<Int64>() < 0) ||
                (type == Field::Types::UInt64 && parameters[i].get<UInt64>() == 0))
            throw Exception("Parameter for aggregate function " + name + " should be positive number", ErrorCodes::BAD_ARGUMENTS);

        return parameters[i].get<UInt64>();
    };

    UInt64 max_elems = get_parameter(0);

    UInt64 seed;
    if (parameters.size() >= 2)
        seed = get_parameter(1);
    else
        seed = thread_local_rng();

    return createAggregateFunctionGroupArrayImpl<GroupArrayTrait<true, Sampler::RNG>>(argument_types[0], parameters, max_elems, seed);
}

}


void registerAggregateFunctionGroupArray(AggregateFunctionFactory & factory)
{
    AggregateFunctionProperties properties = { .returns_default_when_only_null = false, .is_order_dependent = true };

    factory.registerFunction("groupArray", { createAggregateFunctionGroupArray, properties });
    factory.registerFunction("groupArraySample", { createAggregateFunctionGroupArraySample, properties });
}

}