ClickHouse/dbms/include/DB/AggregateFunctions/AggregateFunctionsArgMinMax.h
2017-03-09 07:26:17 +03:00

75 lines
2.1 KiB
C++

#pragma once
#include <DB/AggregateFunctions/AggregateFunctionsMinMaxAny.h>
#include <DB/AggregateFunctions/IBinaryAggregateFunction.h>
namespace DB
{
/// For possible values for template parameters, see AggregateFunctionsMinMaxAny.h
template <typename ResultData, typename ValueData>
struct AggregateFunctionsArgMinMaxData
{
using ResultData_t = ResultData;
using ValueData_t = ValueData;
ResultData result; // the argument at which the minimum/maximum value is reached.
ValueData value; // value for which the minimum/maximum is calculated.
};
/// Returns the first arg value found for the minimum/maximum value. Example: argMax(arg, value).
template <typename Data>
class AggregateFunctionsArgMinMax final : public IBinaryAggregateFunction<Data, AggregateFunctionsArgMinMax<Data>>
{
private:
DataTypePtr type_res;
DataTypePtr type_val;
public:
String getName() const override { return (0 == strcmp(Data::ValueData_t::name(), "min")) ? "argMin" : "argMax"; }
DataTypePtr getReturnType() const override
{
return type_res;
}
void setArgumentsImpl(const DataTypes & arguments)
{
type_res = arguments[0];
type_val = arguments[1];
}
void addImpl(AggregateDataPtr place, const IColumn & column_arg, const IColumn & column_max, size_t row_num, Arena *) const
{
if (this->data(place).value.changeIfBetter(column_max, row_num))
this->data(place).result.change(column_arg, row_num);
}
void merge(AggregateDataPtr place, ConstAggregateDataPtr rhs, Arena * arena) const override
{
if (this->data(place).value.changeIfBetter(this->data(rhs).value))
this->data(place).result.change(this->data(rhs).result);
}
void serialize(ConstAggregateDataPtr place, WriteBuffer & buf) const override
{
this->data(place).result.write(buf, *type_res.get());
this->data(place).value.write(buf, *type_val.get());
}
void deserialize(AggregateDataPtr place, ReadBuffer & buf, Arena *) const override
{
this->data(place).result.read(buf, *type_res.get());
this->data(place).value.read(buf, *type_val.get());
}
void insertResultInto(ConstAggregateDataPtr place, IColumn & to) const override
{
this->data(place).result.insertResultInto(to);
}
};
}